libata: beef up iterators

[linux-2.6-omap-h63xx.git] / drivers / ata / libata-eh.c

/*
 *  libata-eh.c - libata error handling
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2006 Tejun Heo <htejun@gmail.com>
 *
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation; either version 2, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 *  USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 *
 */

#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/pci.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>
#include "../scsi/scsi_transport_api.h"

#include <linux/libata.h>

#include "libata.h"

enum {
        /* speed down verdicts */
        ATA_EH_SPDN_NCQ_OFF             = (1 << 0),
        ATA_EH_SPDN_SPEED_DOWN          = (1 << 1),
        ATA_EH_SPDN_FALLBACK_TO_PIO     = (1 << 2),
        ATA_EH_SPDN_KEEP_ERRORS         = (1 << 3),

        /* error flags */
        ATA_EFLAG_IS_IO                 = (1 << 0),
        ATA_EFLAG_DUBIOUS_XFER          = (1 << 1),

        /* error categories */
        ATA_ECAT_NONE                   = 0,
        ATA_ECAT_ATA_BUS                = 1,
        ATA_ECAT_TOUT_HSM               = 2,
        ATA_ECAT_UNK_DEV                = 3,
        ATA_ECAT_DUBIOUS_NONE           = 4,
        ATA_ECAT_DUBIOUS_ATA_BUS        = 5,
        ATA_ECAT_DUBIOUS_TOUT_HSM       = 6,
        ATA_ECAT_DUBIOUS_UNK_DEV        = 7,
        ATA_ECAT_NR                     = 8,

        ATA_EH_CMD_DFL_TIMEOUT          =  5000,

        /* always put at least this amount of time between resets */
        ATA_EH_RESET_COOL_DOWN          =  5000,

        /* Waiting in ->prereset can never be reliable.  It's
         * sometimes nice to wait there but it can't be depended upon;
         * otherwise, we wouldn't be resetting.  Just give it enough
         * time for most drives to spin up.
         */
        ATA_EH_PRERESET_TIMEOUT         = 10000,
        ATA_EH_FASTDRAIN_INTERVAL       =  3000,

        ATA_EH_UA_TRIES                 = 5,
};

/* The following table determines how we sequence resets.  Each entry
 * represents timeout for that try.  The first try can be soft or
 * hardreset.  All others are hardreset if available.  In most cases
 * the first reset w/ 10sec timeout should succeed.  Following entries
 * are mostly for error handling, hotplug and retarded devices.
 */
static const unsigned long ata_eh_reset_timeouts[] = {
        10000,  /* most drives spin up by 10sec */
        10000,  /* > 99% working drives spin up before 20sec */
        35000,  /* give > 30 secs of idleness for retarded devices */
         5000,  /* and sweet one last chance */
        ULONG_MAX, /* > 1 min has elapsed, give up */
};

static const unsigned long ata_eh_identify_timeouts[] = {
         5000,  /* covers > 99% of successes and not too boring on failures */
        10000,  /* combined time till here is enough even for media access */
        30000,  /* for true idiots */
        ULONG_MAX,
};

static const unsigned long ata_eh_other_timeouts[] = {
         5000,  /* same rationale as identify timeout */
        10000,  /* ditto */
        /* but no merciful 30sec for other commands, it just isn't worth it */
        ULONG_MAX,
};

struct ata_eh_cmd_timeout_ent {
        const u8                *commands;
        const unsigned long     *timeouts;
};

/* The following table determines timeouts to use for EH internal
 * commands.  Each table entry is a command class and matches the
 * commands the entry applies to and the timeout table to use.
 *
 * On the retry after a command timed out, the next timeout value from
 * the table is used.  If the table doesn't contain further entries,
 * the last value is used.
 *
 * ehc->cmd_timeout_idx keeps track of which timeout to use per
 * command class, so if SET_FEATURES times out on the first try, the
 * next try will use the second timeout value only for that class.
 */
#define CMDS(cmds...)   (const u8 []){ cmds, 0 }
static const struct ata_eh_cmd_timeout_ent
ata_eh_cmd_timeout_table[ATA_EH_CMD_TIMEOUT_TABLE_SIZE] = {
        { .commands = CMDS(ATA_CMD_ID_ATA, ATA_CMD_ID_ATAPI),
          .timeouts = ata_eh_identify_timeouts, },
        { .commands = CMDS(ATA_CMD_READ_NATIVE_MAX, ATA_CMD_READ_NATIVE_MAX_EXT),
          .timeouts = ata_eh_other_timeouts, },
        { .commands = CMDS(ATA_CMD_SET_MAX, ATA_CMD_SET_MAX_EXT),
          .timeouts = ata_eh_other_timeouts, },
        { .commands = CMDS(ATA_CMD_SET_FEATURES),
          .timeouts = ata_eh_other_timeouts, },
        { .commands = CMDS(ATA_CMD_INIT_DEV_PARAMS),
          .timeouts = ata_eh_other_timeouts, },
};
#undef CMDS

static void __ata_port_freeze(struct ata_port *ap);
#ifdef CONFIG_PM
static void ata_eh_handle_port_suspend(struct ata_port *ap);
static void ata_eh_handle_port_resume(struct ata_port *ap);
#else /* CONFIG_PM */
static void ata_eh_handle_port_suspend(struct ata_port *ap)
{ }

static void ata_eh_handle_port_resume(struct ata_port *ap)
{ }
#endif /* CONFIG_PM */

static void __ata_ehi_pushv_desc(struct ata_eh_info *ehi, const char *fmt,
                                 va_list args)
{
        ehi->desc_len += vscnprintf(ehi->desc + ehi->desc_len,
                                     ATA_EH_DESC_LEN - ehi->desc_len,
                                     fmt, args);
}

/**
 *      __ata_ehi_push_desc - push error description without adding separator
 *      @ehi: target EHI
 *      @fmt: printf format string
 *
 *      Format string according to @fmt and append it to @ehi->desc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        __ata_ehi_pushv_desc(ehi, fmt, args);
        va_end(args);
}

/**
 *      ata_ehi_push_desc - push error description with separator
 *      @ehi: target EHI
 *      @fmt: printf format string
 *
 *      Format string according to @fmt and append it to @ehi->desc.
 *      If @ehi->desc is not empty, ", " is added in-between.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
{
        va_list args;

        if (ehi->desc_len)
                __ata_ehi_push_desc(ehi, ", ");

        va_start(args, fmt);
        __ata_ehi_pushv_desc(ehi, fmt, args);
        va_end(args);
}

/**
 *      ata_ehi_clear_desc - clean error description
 *      @ehi: target EHI
 *
 *      Clear @ehi->desc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_ehi_clear_desc(struct ata_eh_info *ehi)
{
        ehi->desc[0] = '\0';
        ehi->desc_len = 0;
}

/**
 *      ata_port_desc - append port description
 *      @ap: target ATA port
 *      @fmt: printf format string
 *
 *      Format string according to @fmt and append it to port
 *      description.  If port description is not empty, " " is added
 *      in-between.  This function is to be used while initializing
 *      ata_host.  The description is printed on host registration.
 *
 *      LOCKING:
 *      None.
 */
void ata_port_desc(struct ata_port *ap, const char *fmt, ...)
{
        va_list args;

        WARN_ON(!(ap->pflags & ATA_PFLAG_INITIALIZING));

        if (ap->link.eh_info.desc_len)
                __ata_ehi_push_desc(&ap->link.eh_info, " ");

        va_start(args, fmt);
        __ata_ehi_pushv_desc(&ap->link.eh_info, fmt, args);
        va_end(args);
}

#ifdef CONFIG_PCI

/**
 *      ata_port_pbar_desc - append PCI BAR description
 *      @ap: target ATA port
 *      @bar: target PCI BAR
 *      @offset: offset into PCI BAR
 *      @name: name of the area
 *
 *      If @offset is negative, this function formats a string which
 *      contains the name, address, size and type of the BAR and
 *      appends it to the port description.  If @offset is zero or
 *      positive, only name and offsetted address is appended.
 *
 *      LOCKING:
 *      None.
 */
void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
                        const char *name)
{
        struct pci_dev *pdev = to_pci_dev(ap->host->dev);
        char *type = "";
        unsigned long long start, len;

        if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
                type = "m";
        else if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
                type = "i";

        start = (unsigned long long)pci_resource_start(pdev, bar);
        len = (unsigned long long)pci_resource_len(pdev, bar);

        if (offset < 0)
                ata_port_desc(ap, "%s %s%llu@0x%llx", name, type, len, start);
        else
                ata_port_desc(ap, "%s 0x%llx", name,
                                start + (unsigned long long)offset);
}

#endif /* CONFIG_PCI */

static int ata_lookup_timeout_table(u8 cmd)
{
        int i;

        for (i = 0; i < ATA_EH_CMD_TIMEOUT_TABLE_SIZE; i++) {
                const u8 *cur;

                for (cur = ata_eh_cmd_timeout_table[i].commands; *cur; cur++)
                        if (*cur == cmd)
                                return i;
        }

        return -1;
}

/**
 *      ata_internal_cmd_timeout - determine timeout for an internal command
 *      @dev: target device
 *      @cmd: internal command to be issued
 *
 *      Determine timeout for internal command @cmd for @dev.
 *
 *      LOCKING:
 *      EH context.
 *
 *      RETURNS:
 *      Determined timeout.
 */
unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;
        int ent = ata_lookup_timeout_table(cmd);
        int idx;

        if (ent < 0)
                return ATA_EH_CMD_DFL_TIMEOUT;

        idx = ehc->cmd_timeout_idx[dev->devno][ent];
        return ata_eh_cmd_timeout_table[ent].timeouts[idx];
}

/**
 *      ata_internal_cmd_timed_out - notification for internal command timeout
 *      @dev: target device
 *      @cmd: internal command which timed out
 *
 *      Notify EH that internal command @cmd for @dev timed out.  This
 *      function should be called only for commands whose timeouts are
 *      determined using ata_internal_cmd_timeout().
 *
 *      LOCKING:
 *      EH context.
 */
void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;
        int ent = ata_lookup_timeout_table(cmd);
        int idx;

        if (ent < 0)
                return;

        idx = ehc->cmd_timeout_idx[dev->devno][ent];
        if (ata_eh_cmd_timeout_table[ent].timeouts[idx + 1] != ULONG_MAX)
                ehc->cmd_timeout_idx[dev->devno][ent]++;
}

static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,
                             unsigned int err_mask)
{
        struct ata_ering_entry *ent;

        WARN_ON(!err_mask);

        ering->cursor++;
        ering->cursor %= ATA_ERING_SIZE;

        ent = &ering->ring[ering->cursor];
        ent->eflags = eflags;
        ent->err_mask = err_mask;
        ent->timestamp = get_jiffies_64();
}

static struct ata_ering_entry *ata_ering_top(struct ata_ering *ering)
{
        struct ata_ering_entry *ent = &ering->ring[ering->cursor];

        if (ent->err_mask)
                return ent;
        return NULL;
}

static void ata_ering_clear(struct ata_ering *ering)
{
        memset(ering, 0, sizeof(*ering));
}

static int ata_ering_map(struct ata_ering *ering,
                         int (*map_fn)(struct ata_ering_entry *, void *),
                         void *arg)
{
        int idx, rc = 0;
        struct ata_ering_entry *ent;

        idx = ering->cursor;
        do {
                ent = &ering->ring[idx];
                if (!ent->err_mask)
                        break;
                rc = map_fn(ent, arg);
                if (rc)
                        break;
                idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
        } while (idx != ering->cursor);

        return rc;
}

static unsigned int ata_eh_dev_action(struct ata_device *dev)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;

        return ehc->i.action | ehc->i.dev_action[dev->devno];
}

static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
                                struct ata_eh_info *ehi, unsigned int action)
{
        struct ata_device *tdev;

        if (!dev) {
                ehi->action &= ~action;
                ata_for_each_dev(tdev, link, ALL)
                        ehi->dev_action[tdev->devno] &= ~action;
        } else {
                /* doesn't make sense for port-wide EH actions */
                WARN_ON(!(action & ATA_EH_PERDEV_MASK));

                /* break ehi->action into ehi->dev_action */
                if (ehi->action & action) {
                        ata_for_each_dev(tdev, link, ALL)
                                ehi->dev_action[tdev->devno] |=
                                        ehi->action & action;
                        ehi->action &= ~action;
                }

                /* turn off the specified per-dev action */
                ehi->dev_action[dev->devno] &= ~action;
        }
}

/**
 *      ata_scsi_timed_out - SCSI layer time out callback
 *      @cmd: timed out SCSI command
 *
 *      Handles SCSI layer timeout.  We race with normal completion of
 *      the qc for @cmd.  If the qc is already gone, we lose and let
 *      the scsi command finish (EH_HANDLED).  Otherwise, the qc has
 *      timed out and EH should be invoked.  Prevent ata_qc_complete()
 *      from finishing it by setting EH_SCHEDULED and return
 *      EH_NOT_HANDLED.
 *
 *      TODO: kill this function once old EH is gone.
 *
 *      LOCKING:
 *      Called from timer context
 *
 *      RETURNS:
 *      EH_HANDLED or EH_NOT_HANDLED
 */
enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *host = cmd->device->host;
        struct ata_port *ap = ata_shost_to_port(host);
        unsigned long flags;
        struct ata_queued_cmd *qc;
        enum blk_eh_timer_return ret;

        DPRINTK("ENTER\n");

        if (ap->ops->error_handler) {
                ret = BLK_EH_NOT_HANDLED;
                goto out;
        }

        ret = BLK_EH_HANDLED;
        spin_lock_irqsave(ap->lock, flags);
        qc = ata_qc_from_tag(ap, ap->link.active_tag);
        if (qc) {
                WARN_ON(qc->scsicmd != cmd);
                qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
                qc->err_mask |= AC_ERR_TIMEOUT;
                ret = BLK_EH_NOT_HANDLED;
        }
        spin_unlock_irqrestore(ap->lock, flags);

 out:
        DPRINTK("EXIT, ret=%d\n", ret);
        return ret;
}

/**
 *      ata_scsi_error - SCSI layer error handler callback
 *      @host: SCSI host on which error occurred
 *
 *      Handles SCSI-layer-thrown error events.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 *
 *      RETURNS:
 *      Zero.
 */
void ata_scsi_error(struct Scsi_Host *host)
{
        struct ata_port *ap = ata_shost_to_port(host);
        int i;
        unsigned long flags;

        DPRINTK("ENTER\n");

        /* synchronize with port task */
        ata_port_flush_task(ap);

        /* synchronize with host lock and sort out timeouts */

        /* For new EH, all qcs are finished in one of three ways -
         * normal completion, error completion, and SCSI timeout.
         * Both cmpletions can race against SCSI timeout.  When normal
         * completion wins, the qc never reaches EH.  When error
         * completion wins, the qc has ATA_QCFLAG_FAILED set.
         *
         * When SCSI timeout wins, things are a bit more complex.
         * Normal or error completion can occur after the timeout but
         * before this point.  In such cases, both types of
         * completions are honored.  A scmd is determined to have
         * timed out iff its associated qc is active and not failed.
         */
        if (ap->ops->error_handler) {
                struct scsi_cmnd *scmd, *tmp;
                int nr_timedout = 0;

                spin_lock_irqsave(ap->lock, flags);

                list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
                        struct ata_queued_cmd *qc;

                        for (i = 0; i < ATA_MAX_QUEUE; i++) {
                                qc = __ata_qc_from_tag(ap, i);
                                if (qc->flags & ATA_QCFLAG_ACTIVE &&
                                    qc->scsicmd == scmd)
                                        break;
                        }

                        if (i < ATA_MAX_QUEUE) {
                                /* the scmd has an associated qc */
                                if (!(qc->flags & ATA_QCFLAG_FAILED)) {
                                        /* which hasn't failed yet, timeout */
                                        qc->err_mask |= AC_ERR_TIMEOUT;
                                        qc->flags |= ATA_QCFLAG_FAILED;
                                        nr_timedout++;
                                }
                        } else {
                                /* Normal completion occurred after
                                 * SCSI timeout but before this point.
                                 * Successfully complete it.
                                 */
                                scmd->retries = scmd->allowed;
                                scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
                        }
                }

                /* If we have timed out qcs.  They belong to EH from
                 * this point but the state of the controller is
                 * unknown.  Freeze the port to make sure the IRQ
                 * handler doesn't diddle with those qcs.  This must
                 * be done atomically w.r.t. setting QCFLAG_FAILED.
                 */
                if (nr_timedout)
                        __ata_port_freeze(ap);

                spin_unlock_irqrestore(ap->lock, flags);

                /* initialize eh_tries */
                ap->eh_tries = ATA_EH_MAX_TRIES;
        } else
                spin_unlock_wait(ap->lock);

 repeat:
        /* invoke error handler */
        if (ap->ops->error_handler) {
                struct ata_link *link;

                /* kill fast drain timer */
                del_timer_sync(&ap->fastdrain_timer);

                /* process port resume request */
                ata_eh_handle_port_resume(ap);

                /* fetch & clear EH info */
                spin_lock_irqsave(ap->lock, flags);

                ata_for_each_link(link, ap, HOST_FIRST) {
                        struct ata_eh_context *ehc = &link->eh_context;
                        struct ata_device *dev;

                        memset(&link->eh_context, 0, sizeof(link->eh_context));
                        link->eh_context.i = link->eh_info;
                        memset(&link->eh_info, 0, sizeof(link->eh_info));

                        ata_for_each_dev(dev, link, ENABLED) {
                                int devno = dev->devno;

                                ehc->saved_xfer_mode[devno] = dev->xfer_mode;
                                if (ata_ncq_enabled(dev))
                                        ehc->saved_ncq_enabled |= 1 << devno;
                        }
                }

                ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
                ap->pflags &= ~ATA_PFLAG_EH_PENDING;
                ap->excl_link = NULL;   /* don't maintain exclusion over EH */

                spin_unlock_irqrestore(ap->lock, flags);

                /* invoke EH, skip if unloading or suspended */
                if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
                        ap->ops->error_handler(ap);
                else
                        ata_eh_finish(ap);

                /* process port suspend request */
                ata_eh_handle_port_suspend(ap);

                /* Exception might have happend after ->error_handler
                 * recovered the port but before this point.  Repeat
                 * EH in such case.
                 */
                spin_lock_irqsave(ap->lock, flags);

                if (ap->pflags & ATA_PFLAG_EH_PENDING) {
                        if (--ap->eh_tries) {
                                spin_unlock_irqrestore(ap->lock, flags);
                                goto repeat;
                        }
                        ata_port_printk(ap, KERN_ERR, "EH pending after %d "
                                        "tries, giving up\n", ATA_EH_MAX_TRIES);
                        ap->pflags &= ~ATA_PFLAG_EH_PENDING;
                }

                /* this run is complete, make sure EH info is clear */
                ata_for_each_link(link, ap, HOST_FIRST)
                        memset(&link->eh_info, 0, sizeof(link->eh_info));

                /* Clear host_eh_scheduled while holding ap->lock such
                 * that if exception occurs after this point but
                 * before EH completion, SCSI midlayer will
                 * re-initiate EH.
                 */
                host->host_eh_scheduled = 0;

                spin_unlock_irqrestore(ap->lock, flags);
        } else {
                WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
                ap->ops->eng_timeout(ap);
        }

        /* finish or retry handled scmd's and clean up */
        WARN_ON(host->host_failed || !list_empty(&host->eh_cmd_q));

        scsi_eh_flush_done_q(&ap->eh_done_q);

        /* clean up */
        spin_lock_irqsave(ap->lock, flags);

        if (ap->pflags & ATA_PFLAG_LOADING)
                ap->pflags &= ~ATA_PFLAG_LOADING;
        else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
                queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0);

        if (ap->pflags & ATA_PFLAG_RECOVERED)
                ata_port_printk(ap, KERN_INFO, "EH complete\n");

        ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);

        /* tell wait_eh that we're done */
        ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;
        wake_up_all(&ap->eh_wait_q);

        spin_unlock_irqrestore(ap->lock, flags);

        DPRINTK("EXIT\n");
}

/**
 *      ata_port_wait_eh - Wait for the currently pending EH to complete
 *      @ap: Port to wait EH for
 *
 *      Wait until the currently pending EH is complete.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_port_wait_eh(struct ata_port *ap)
{
        unsigned long flags;
        DEFINE_WAIT(wait);

 retry:
        spin_lock_irqsave(ap->lock, flags);

        while (ap->pflags & (ATA_PFLAG_EH_PENDING | ATA_PFLAG_EH_IN_PROGRESS)) {
                prepare_to_wait(&ap->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
                spin_unlock_irqrestore(ap->lock, flags);
                schedule();
                spin_lock_irqsave(ap->lock, flags);
        }
        finish_wait(&ap->eh_wait_q, &wait);

        spin_unlock_irqrestore(ap->lock, flags);

        /* make sure SCSI EH is complete */
        if (scsi_host_in_recovery(ap->scsi_host)) {
                msleep(10);
                goto retry;
        }
}

static int ata_eh_nr_in_flight(struct ata_port *ap)
{
        unsigned int tag;
        int nr = 0;

        /* count only non-internal commands */
        for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
                if (ata_qc_from_tag(ap, tag))
                        nr++;

        return nr;
}

void ata_eh_fastdrain_timerfn(unsigned long arg)
{
        struct ata_port *ap = (void *)arg;
        unsigned long flags;
        int cnt;

        spin_lock_irqsave(ap->lock, flags);

        cnt = ata_eh_nr_in_flight(ap);

        /* are we done? */
        if (!cnt)
                goto out_unlock;

        if (cnt == ap->fastdrain_cnt) {
                unsigned int tag;

                /* No progress during the last interval, tag all
                 * in-flight qcs as timed out and freeze the port.
                 */
                for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
                        struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
                        if (qc)
                                qc->err_mask |= AC_ERR_TIMEOUT;
                }

                ata_port_freeze(ap);
        } else {
                /* some qcs have finished, give it another chance */
                ap->fastdrain_cnt = cnt;
                ap->fastdrain_timer.expires =
                        ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
                add_timer(&ap->fastdrain_timer);
        }

 out_unlock:
        spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *      ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
 *      @ap: target ATA port
 *      @fastdrain: activate fast drain
 *
 *      Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
 *      is non-zero and EH wasn't pending before.  Fast drain ensures
 *      that EH kicks in in timely manner.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
{
        int cnt;

        /* already scheduled? */
        if (ap->pflags & ATA_PFLAG_EH_PENDING)
                return;

        ap->pflags |= ATA_PFLAG_EH_PENDING;

        if (!fastdrain)
                return;

        /* do we have in-flight qcs? */
        cnt = ata_eh_nr_in_flight(ap);
        if (!cnt)
                return;

        /* activate fast drain */
        ap->fastdrain_cnt = cnt;
        ap->fastdrain_timer.expires =
                ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
        add_timer(&ap->fastdrain_timer);
}

/**
 *      ata_qc_schedule_eh - schedule qc for error handling
 *      @qc: command to schedule error handling for
 *
 *      Schedule error handling for @qc.  EH will kick in as soon as
 *      other commands are drained.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        WARN_ON(!ap->ops->error_handler);

        qc->flags |= ATA_QCFLAG_FAILED;
        ata_eh_set_pending(ap, 1);

        /* The following will fail if timeout has already expired.
         * ata_scsi_error() takes care of such scmds on EH entry.
         * Note that ATA_QCFLAG_FAILED is unconditionally set after
         * this function completes.
         */
        blk_abort_request(qc->scsicmd->request);
}

/**
 *      ata_port_schedule_eh - schedule error handling without a qc
 *      @ap: ATA port to schedule EH for
 *
 *      Schedule error handling for @ap.  EH will kick in as soon as
 *      all commands are drained.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
void ata_port_schedule_eh(struct ata_port *ap)
{
        WARN_ON(!ap->ops->error_handler);

        if (ap->pflags & ATA_PFLAG_INITIALIZING)
                return;

        ata_eh_set_pending(ap, 1);
        scsi_schedule_eh(ap->scsi_host);

        DPRINTK("port EH scheduled\n");
}

static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
{
        int tag, nr_aborted = 0;

        WARN_ON(!ap->ops->error_handler);

        /* we're gonna abort all commands, no need for fast drain */
        ata_eh_set_pending(ap, 0);

        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);

                if (qc && (!link || qc->dev->link == link)) {
                        qc->flags |= ATA_QCFLAG_FAILED;
                        ata_qc_complete(qc);
                        nr_aborted++;
                }
        }

        if (!nr_aborted)
                ata_port_schedule_eh(ap);

        return nr_aborted;
}

/**
 *      ata_link_abort - abort all qc's on the link
 *      @link: ATA link to abort qc's for
 *
 *      Abort all active qc's active on @link and schedule EH.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      Number of aborted qc's.
 */
int ata_link_abort(struct ata_link *link)
{
        return ata_do_link_abort(link->ap, link);
}

/**
 *      ata_port_abort - abort all qc's on the port
 *      @ap: ATA port to abort qc's for
 *
 *      Abort all active qc's of @ap and schedule EH.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Number of aborted qc's.
 */
int ata_port_abort(struct ata_port *ap)
{
        return ata_do_link_abort(ap, NULL);
}

/**
 *      __ata_port_freeze - freeze port
 *      @ap: ATA port to freeze
 *
 *      This function is called when HSM violation or some other
 *      condition disrupts normal operation of the port.  Frozen port
 *      is not allowed to perform any operation until the port is
 *      thawed, which usually follows a successful reset.
 *
 *      ap->ops->freeze() callback can be used for freezing the port
 *      hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
 *      port cannot be frozen hardware-wise, the interrupt handler
 *      must ack and clear interrupts unconditionally while the port
 *      is frozen.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 */
static void __ata_port_freeze(struct ata_port *ap)
{
        WARN_ON(!ap->ops->error_handler);

        if (ap->ops->freeze)
                ap->ops->freeze(ap);

        ap->pflags |= ATA_PFLAG_FROZEN;

        DPRINTK("ata%u port frozen\n", ap->print_id);
}

/**
 *      ata_port_freeze - abort & freeze port
 *      @ap: ATA port to freeze
 *
 *      Abort and freeze @ap.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      Number of aborted commands.
 */
int ata_port_freeze(struct ata_port *ap)
{
        int nr_aborted;

        WARN_ON(!ap->ops->error_handler);

        nr_aborted = ata_port_abort(ap);
        __ata_port_freeze(ap);

        return nr_aborted;
}

/**
 *      sata_async_notification - SATA async notification handler
 *      @ap: ATA port where async notification is received
 *
 *      Handler to be called when async notification via SDB FIS is
 *      received.  This function schedules EH if necessary.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host lock)
 *
 *      RETURNS:
 *      1 if EH is scheduled, 0 otherwise.
 */
int sata_async_notification(struct ata_port *ap)
{
        u32 sntf;
        int rc;

        if (!(ap->flags & ATA_FLAG_AN))
                return 0;

        rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
        if (rc == 0)
                sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);

        if (!sata_pmp_attached(ap) || rc) {
                /* PMP is not attached or SNTF is not available */
                if (!sata_pmp_attached(ap)) {
                        /* PMP is not attached.  Check whether ATAPI
                         * AN is configured.  If so, notify media
                         * change.
                         */
                        struct ata_device *dev = ap->link.device;

                        if ((dev->class == ATA_DEV_ATAPI) &&
                            (dev->flags & ATA_DFLAG_AN))
                                ata_scsi_media_change_notify(dev);
                        return 0;
                } else {
                        /* PMP is attached but SNTF is not available.
                         * ATAPI async media change notification is
                         * not used.  The PMP must be reporting PHY
                         * status change, schedule EH.
                         */
                        ata_port_schedule_eh(ap);
                        return 1;
                }
        } else {
                /* PMP is attached and SNTF is available */
                struct ata_link *link;

                /* check and notify ATAPI AN */
                ata_for_each_link(link, ap, EDGE) {
                        if (!(sntf & (1 << link->pmp)))
                                continue;

                        if ((link->device->class == ATA_DEV_ATAPI) &&
                            (link->device->flags & ATA_DFLAG_AN))
                                ata_scsi_media_change_notify(link->device);
                }

                /* If PMP is reporting that PHY status of some
                 * downstream ports has changed, schedule EH.
                 */
                if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
                        ata_port_schedule_eh(ap);
                        return 1;
                }

                return 0;
        }
}

/**
 *      ata_eh_freeze_port - EH helper to freeze port
 *      @ap: ATA port to freeze
 *
 *      Freeze @ap.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_freeze_port(struct ata_port *ap)
{
        unsigned long flags;

        if (!ap->ops->error_handler)
                return;

        spin_lock_irqsave(ap->lock, flags);
        __ata_port_freeze(ap);
        spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *      ata_port_thaw_port - EH helper to thaw port
 *      @ap: ATA port to thaw
 *
 *      Thaw frozen port @ap.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_thaw_port(struct ata_port *ap)
{
        unsigned long flags;

        if (!ap->ops->error_handler)
                return;

        spin_lock_irqsave(ap->lock, flags);

        ap->pflags &= ~ATA_PFLAG_FROZEN;

        if (ap->ops->thaw)
                ap->ops->thaw(ap);

        spin_unlock_irqrestore(ap->lock, flags);

        DPRINTK("ata%u port thawed\n", ap->print_id);
}

static void ata_eh_scsidone(struct scsi_cmnd *scmd)
{
        /* nada */
}

static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scsi_cmnd *scmd = qc->scsicmd;
        unsigned long flags;

        spin_lock_irqsave(ap->lock, flags);
        qc->scsidone = ata_eh_scsidone;
        __ata_qc_complete(qc);
        WARN_ON(ata_tag_valid(qc->tag));
        spin_unlock_irqrestore(ap->lock, flags);

        scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
}

/**
 *      ata_eh_qc_complete - Complete an active ATA command from EH
 *      @qc: Command to complete
 *
 *      Indicate to the mid and upper layers that an ATA command has
 *      completed.  To be used from EH.
 */
void ata_eh_qc_complete(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *scmd = qc->scsicmd;
        scmd->retries = scmd->allowed;
        __ata_eh_qc_complete(qc);
}

/**
 *      ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
 *      @qc: Command to retry
 *
 *      Indicate to the mid and upper layers that an ATA command
 *      should be retried.  To be used from EH.
 *
 *      SCSI midlayer limits the number of retries to scmd->allowed.
 *      scmd->retries is decremented for commands which get retried
 *      due to unrelated failures (qc->err_mask is zero).
 */
void ata_eh_qc_retry(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *scmd = qc->scsicmd;
        if (!qc->err_mask && scmd->retries)
                scmd->retries--;
        __ata_eh_qc_complete(qc);
}

/**
 *      ata_eh_detach_dev - detach ATA device
 *      @dev: ATA device to detach
 *
 *      Detach @dev.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_detach_dev(struct ata_device *dev)
{
        struct ata_link *link = dev->link;
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        unsigned long flags;

        ata_dev_disable(dev);

        spin_lock_irqsave(ap->lock, flags);

        dev->flags &= ~ATA_DFLAG_DETACH;

        if (ata_scsi_offline_dev(dev)) {
                dev->flags |= ATA_DFLAG_DETACHED;
                ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
        }

        /* clear per-dev EH info */
        ata_eh_clear_action(link, dev, &link->eh_info, ATA_EH_PERDEV_MASK);
        ata_eh_clear_action(link, dev, &link->eh_context.i, ATA_EH_PERDEV_MASK);
        ehc->saved_xfer_mode[dev->devno] = 0;
        ehc->saved_ncq_enabled &= ~(1 << dev->devno);

        spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *      ata_eh_about_to_do - about to perform eh_action
 *      @link: target ATA link
 *      @dev: target ATA dev for per-dev action (can be NULL)
 *      @action: action about to be performed
 *
 *      Called just before performing EH actions to clear related bits
 *      in @link->eh_info such that eh actions are not unnecessarily
 *      repeated.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
                        unsigned int action)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_info *ehi = &link->eh_info;
        struct ata_eh_context *ehc = &link->eh_context;
        unsigned long flags;

        spin_lock_irqsave(ap->lock, flags);

        ata_eh_clear_action(link, dev, ehi, action);

        /* About to take EH action, set RECOVERED.  Ignore actions on
         * slave links as master will do them again.
         */
        if (!(ehc->i.flags & ATA_EHI_QUIET) && link != ap->slave_link)
                ap->pflags |= ATA_PFLAG_RECOVERED;

        spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *      ata_eh_done - EH action complete
*       @ap: target ATA port
 *      @dev: target ATA dev for per-dev action (can be NULL)
 *      @action: action just completed
 *
 *      Called right after performing EH actions to clear related bits
 *      in @link->eh_context.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_done(struct ata_link *link, struct ata_device *dev,
                 unsigned int action)
{
        struct ata_eh_context *ehc = &link->eh_context;

        ata_eh_clear_action(link, dev, &ehc->i, action);
}

/**
 *      ata_err_string - convert err_mask to descriptive string
 *      @err_mask: error mask to convert to string
 *
 *      Convert @err_mask to descriptive string.  Errors are
 *      prioritized according to severity and only the most severe
 *      error is reported.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Descriptive string for @err_mask
 */
static const char *ata_err_string(unsigned int err_mask)
{
        if (err_mask & AC_ERR_HOST_BUS)
                return "host bus error";
        if (err_mask & AC_ERR_ATA_BUS)
                return "ATA bus error";
        if (err_mask & AC_ERR_TIMEOUT)
                return "timeout";
        if (err_mask & AC_ERR_HSM)
                return "HSM violation";
        if (err_mask & AC_ERR_SYSTEM)
                return "internal error";
        if (err_mask & AC_ERR_MEDIA)
                return "media error";
        if (err_mask & AC_ERR_INVALID)
                return "invalid argument";
        if (err_mask & AC_ERR_DEV)
                return "device error";
        return "unknown error";
}

/**
 *      ata_read_log_page - read a specific log page
 *      @dev: target device
 *      @page: page to read
 *      @buf: buffer to store read page
 *      @sectors: number of sectors to read
 *
 *      Read log page using READ_LOG_EXT command.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */
static unsigned int ata_read_log_page(struct ata_device *dev,
                                      u8 page, void *buf, unsigned int sectors)
{
        struct ata_taskfile tf;
        unsigned int err_mask;

        DPRINTK("read log page - page %d\n", page);

        ata_tf_init(dev, &tf);
        tf.command = ATA_CMD_READ_LOG_EXT;
        tf.lbal = page;
        tf.nsect = sectors;
        tf.hob_nsect = sectors >> 8;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_PIO;

        err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
                                     buf, sectors * ATA_SECT_SIZE, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_eh_read_log_10h - Read log page 10h for NCQ error details
 *      @dev: Device to read log page 10h from
 *      @tag: Resulting tag of the failed command
 *      @tf: Resulting taskfile registers of the failed command
 *
 *      Read log page 10h to obtain NCQ error details and clear error
 *      condition.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
static int ata_eh_read_log_10h(struct ata_device *dev,
                               int *tag, struct ata_taskfile *tf)
{
        u8 *buf = dev->link->ap->sector_buf;
        unsigned int err_mask;
        u8 csum;
        int i;

        err_mask = ata_read_log_page(dev, ATA_LOG_SATA_NCQ, buf, 1);
        if (err_mask)
                return -EIO;

        csum = 0;
        for (i = 0; i < ATA_SECT_SIZE; i++)
                csum += buf[i];
        if (csum)
                ata_dev_printk(dev, KERN_WARNING,
                               "invalid checksum 0x%x on log page 10h\n", csum);

        if (buf[0] & 0x80)
                return -ENOENT;

        *tag = buf[0] & 0x1f;

        tf->command = buf[2];
        tf->feature = buf[3];
        tf->lbal = buf[4];
        tf->lbam = buf[5];
        tf->lbah = buf[6];
        tf->device = buf[7];
        tf->hob_lbal = buf[8];
        tf->hob_lbam = buf[9];
        tf->hob_lbah = buf[10];
        tf->nsect = buf[12];
        tf->hob_nsect = buf[13];

        return 0;
}

/**
 *      atapi_eh_tur - perform ATAPI TEST_UNIT_READY
 *      @dev: target ATAPI device
 *      @r_sense_key: out parameter for sense_key
 *
 *      Perform ATAPI TEST_UNIT_READY.
 *
 *      LOCKING:
 *      EH context (may sleep).
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask on failure.
 */
static unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)
{
        u8 cdb[ATAPI_CDB_LEN] = { TEST_UNIT_READY, 0, 0, 0, 0, 0 };
        struct ata_taskfile tf;
        unsigned int err_mask;

        ata_tf_init(dev, &tf);

        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.command = ATA_CMD_PACKET;
        tf.protocol = ATAPI_PROT_NODATA;

        err_mask = ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
        if (err_mask == AC_ERR_DEV)
                *r_sense_key = tf.feature >> 4;
        return err_mask;
}

/**
 *      atapi_eh_request_sense - perform ATAPI REQUEST_SENSE
 *      @dev: device to perform REQUEST_SENSE to
 *      @sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)
 *      @dfl_sense_key: default sense key to use
 *
 *      Perform ATAPI REQUEST_SENSE after the device reported CHECK
 *      SENSE.  This function is EH helper.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask on failure
 */
static unsigned int atapi_eh_request_sense(struct ata_device *dev,
                                           u8 *sense_buf, u8 dfl_sense_key)
{
        u8 cdb[ATAPI_CDB_LEN] =
                { REQUEST_SENSE, 0, 0, 0, SCSI_SENSE_BUFFERSIZE, 0 };
        struct ata_port *ap = dev->link->ap;
        struct ata_taskfile tf;

        DPRINTK("ATAPI request sense\n");

        /* FIXME: is this needed? */
        memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);

        /* initialize sense_buf with the error register,
         * for the case where they are -not- overwritten
         */
        sense_buf[0] = 0x70;
        sense_buf[2] = dfl_sense_key;

        /* some devices time out if garbage left in tf */
        ata_tf_init(dev, &tf);

        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.command = ATA_CMD_PACKET;

        /* is it pointless to prefer PIO for "safety reasons"? */
        if (ap->flags & ATA_FLAG_PIO_DMA) {
                tf.protocol = ATAPI_PROT_DMA;
                tf.feature |= ATAPI_PKT_DMA;
        } else {
                tf.protocol = ATAPI_PROT_PIO;
                tf.lbam = SCSI_SENSE_BUFFERSIZE;
                tf.lbah = 0;
        }

        return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
                                 sense_buf, SCSI_SENSE_BUFFERSIZE, 0);
}

/**
 *      ata_eh_analyze_serror - analyze SError for a failed port
 *      @link: ATA link to analyze SError for
 *
 *      Analyze SError if available and further determine cause of
 *      failure.
 *
 *      LOCKING:
 *      None.
 */
static void ata_eh_analyze_serror(struct ata_link *link)
{
        struct ata_eh_context *ehc = &link->eh_context;
        u32 serror = ehc->i.serror;
        unsigned int err_mask = 0, action = 0;
        u32 hotplug_mask;

        if (serror & (SERR_PERSISTENT | SERR_DATA)) {
                err_mask |= AC_ERR_ATA_BUS;
                action |= ATA_EH_RESET;
        }
        if (serror & SERR_PROTOCOL) {
                err_mask |= AC_ERR_HSM;
                action |= ATA_EH_RESET;
        }
        if (serror & SERR_INTERNAL) {
                err_mask |= AC_ERR_SYSTEM;
                action |= ATA_EH_RESET;
        }

        /* Determine whether a hotplug event has occurred.  Both
         * SError.N/X are considered hotplug events for enabled or
         * host links.  For disabled PMP links, only N bit is
         * considered as X bit is left at 1 for link plugging.
         */
        hotplug_mask = 0;

        if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))
                hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
        else
                hotplug_mask = SERR_PHYRDY_CHG;

        if (serror & hotplug_mask)
                ata_ehi_hotplugged(&ehc->i);

        ehc->i.err_mask |= err_mask;
        ehc->i.action |= action;
}

/**
 *      ata_eh_analyze_ncq_error - analyze NCQ error
 *      @link: ATA link to analyze NCQ error for
 *
 *      Read log page 10h, determine the offending qc and acquire
 *      error status TF.  For NCQ device errors, all LLDDs have to do
 *      is setting AC_ERR_DEV in ehi->err_mask.  This function takes
 *      care of the rest.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_eh_analyze_ncq_error(struct ata_link *link)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        struct ata_device *dev = link->device;
        struct ata_queued_cmd *qc;
        struct ata_taskfile tf;
        int tag, rc;

        /* if frozen, we can't do much */
        if (ap->pflags & ATA_PFLAG_FROZEN)
                return;

        /* is it NCQ device error? */
        if (!link->sactive || !(ehc->i.err_mask & AC_ERR_DEV))
                return;

        /* has LLDD analyzed already? */
        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                qc = __ata_qc_from_tag(ap, tag);

                if (!(qc->flags & ATA_QCFLAG_FAILED))
                        continue;

                if (qc->err_mask)
                        return;
        }

        /* okay, this error is ours */
        rc = ata_eh_read_log_10h(dev, &tag, &tf);
        if (rc) {
                ata_link_printk(link, KERN_ERR, "failed to read log page 10h "
                                "(errno=%d)\n", rc);
                return;
        }

        if (!(link->sactive & (1 << tag))) {
                ata_link_printk(link, KERN_ERR, "log page 10h reported "
                                "inactive tag %d\n", tag);
                return;
        }

        /* we've got the perpetrator, condemn it */
        qc = __ata_qc_from_tag(ap, tag);
        memcpy(&qc->result_tf, &tf, sizeof(tf));
        qc->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
        qc->err_mask |= AC_ERR_DEV | AC_ERR_NCQ;
        ehc->i.err_mask &= ~AC_ERR_DEV;
}

/**
 *      ata_eh_analyze_tf - analyze taskfile of a failed qc
 *      @qc: qc to analyze
 *      @tf: Taskfile registers to analyze
 *
 *      Analyze taskfile of @qc and further determine cause of
 *      failure.  This function also requests ATAPI sense data if
 *      avaliable.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      Determined recovery action
 */
static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
                                      const struct ata_taskfile *tf)
{
        unsigned int tmp, action = 0;
        u8 stat = tf->command, err = tf->feature;

        if ((stat & (ATA_BUSY | ATA_DRQ | ATA_DRDY)) != ATA_DRDY) {
                qc->err_mask |= AC_ERR_HSM;
                return ATA_EH_RESET;
        }

        if (stat & (ATA_ERR | ATA_DF))
                qc->err_mask |= AC_ERR_DEV;
        else
                return 0;

        switch (qc->dev->class) {
        case ATA_DEV_ATA:
                if (err & ATA_ICRC)
                        qc->err_mask |= AC_ERR_ATA_BUS;
                if (err & ATA_UNC)
                        qc->err_mask |= AC_ERR_MEDIA;
                if (err & ATA_IDNF)
                        qc->err_mask |= AC_ERR_INVALID;
                break;

        case ATA_DEV_ATAPI:
                if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
                        tmp = atapi_eh_request_sense(qc->dev,
                                                qc->scsicmd->sense_buffer,
                                                qc->result_tf.feature >> 4);
                        if (!tmp) {
                                /* ATA_QCFLAG_SENSE_VALID is used to
                                 * tell atapi_qc_complete() that sense
                                 * data is already valid.
                                 *
                                 * TODO: interpret sense data and set
                                 * appropriate err_mask.
                                 */
                                qc->flags |= ATA_QCFLAG_SENSE_VALID;
                        } else
                                qc->err_mask |= tmp;
                }
        }

        if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))
                action |= ATA_EH_RESET;

        return action;
}

static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask,
                                   int *xfer_ok)
{
        int base = 0;

        if (!(eflags & ATA_EFLAG_DUBIOUS_XFER))
                *xfer_ok = 1;

        if (!*xfer_ok)
                base = ATA_ECAT_DUBIOUS_NONE;

        if (err_mask & AC_ERR_ATA_BUS)
                return base + ATA_ECAT_ATA_BUS;

        if (err_mask & AC_ERR_TIMEOUT)
                return base + ATA_ECAT_TOUT_HSM;

        if (eflags & ATA_EFLAG_IS_IO) {
                if (err_mask & AC_ERR_HSM)
                        return base + ATA_ECAT_TOUT_HSM;
                if ((err_mask &
                     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
                        return base + ATA_ECAT_UNK_DEV;
        }

        return 0;
}

struct speed_down_verdict_arg {
        u64 since;
        int xfer_ok;
        int nr_errors[ATA_ECAT_NR];
};

static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
{
        struct speed_down_verdict_arg *arg = void_arg;
        int cat;

        if (ent->timestamp < arg->since)
                return -1;

        cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,
                                      &arg->xfer_ok);
        arg->nr_errors[cat]++;

        return 0;
}

/**
 *      ata_eh_speed_down_verdict - Determine speed down verdict
 *      @dev: Device of interest
 *
 *      This function examines error ring of @dev and determines
 *      whether NCQ needs to be turned off, transfer speed should be
 *      stepped down, or falling back to PIO is necessary.
 *
 *      ECAT_ATA_BUS    : ATA_BUS error for any command
 *
 *      ECAT_TOUT_HSM   : TIMEOUT for any command or HSM violation for
 *                        IO commands
 *
 *      ECAT_UNK_DEV    : Unknown DEV error for IO commands
 *
 *      ECAT_DUBIOUS_*  : Identical to above three but occurred while
 *                        data transfer hasn't been verified.
 *
 *      Verdicts are
 *
 *      NCQ_OFF         : Turn off NCQ.
 *
 *      SPEED_DOWN      : Speed down transfer speed but don't fall back
 *                        to PIO.
 *
 *      FALLBACK_TO_PIO : Fall back to PIO.
 *
 *      Even if multiple verdicts are returned, only one action is
 *      taken per error.  An action triggered by non-DUBIOUS errors
 *      clears ering, while one triggered by DUBIOUS_* errors doesn't.
 *      This is to expedite speed down decisions right after device is
 *      initially configured.
 *
 *      The followings are speed down rules.  #1 and #2 deal with
 *      DUBIOUS errors.
 *
 *      1. If more than one DUBIOUS_ATA_BUS or DUBIOUS_TOUT_HSM errors
 *         occurred during last 5 mins, SPEED_DOWN and FALLBACK_TO_PIO.
 *
 *      2. If more than one DUBIOUS_TOUT_HSM or DUBIOUS_UNK_DEV errors
 *         occurred during last 5 mins, NCQ_OFF.
 *
 *      3. If more than 8 ATA_BUS, TOUT_HSM or UNK_DEV errors
 *         ocurred during last 5 mins, FALLBACK_TO_PIO
 *
 *      4. If more than 3 TOUT_HSM or UNK_DEV errors occurred
 *         during last 10 mins, NCQ_OFF.
 *
 *      5. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 6
 *         UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      OR of ATA_EH_SPDN_* flags.
 */
static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
{
        const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
        u64 j64 = get_jiffies_64();
        struct speed_down_verdict_arg arg;
        unsigned int verdict = 0;

        /* scan past 5 mins of error history */
        memset(&arg, 0, sizeof(arg));
        arg.since = j64 - min(j64, j5mins);
        ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

        if (arg.nr_errors[ATA_ECAT_DUBIOUS_ATA_BUS] +
            arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] > 1)
                verdict |= ATA_EH_SPDN_SPEED_DOWN |
                        ATA_EH_SPDN_FALLBACK_TO_PIO | ATA_EH_SPDN_KEEP_ERRORS;

        if (arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] +
            arg.nr_errors[ATA_ECAT_DUBIOUS_UNK_DEV] > 1)
                verdict |= ATA_EH_SPDN_NCQ_OFF | ATA_EH_SPDN_KEEP_ERRORS;

        if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
            arg.nr_errors[ATA_ECAT_TOUT_HSM] +
            arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
                verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;

        /* scan past 10 mins of error history */
        memset(&arg, 0, sizeof(arg));
        arg.since = j64 - min(j64, j10mins);
        ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

        if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
            arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
                verdict |= ATA_EH_SPDN_NCQ_OFF;

        if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
            arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||
            arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
                verdict |= ATA_EH_SPDN_SPEED_DOWN;

        return verdict;
}

/**
 *      ata_eh_speed_down - record error and speed down if necessary
 *      @dev: Failed device
 *      @eflags: mask of ATA_EFLAG_* flags
 *      @err_mask: err_mask of the error
 *
 *      Record error and examine error history to determine whether
 *      adjusting transmission speed is necessary.  It also sets
 *      transmission limits appropriately if such adjustment is
 *      necessary.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      Determined recovery action.
 */
static unsigned int ata_eh_speed_down(struct ata_device *dev,
                                unsigned int eflags, unsigned int err_mask)
{
        struct ata_link *link = ata_dev_phys_link(dev);
        int xfer_ok = 0;
        unsigned int verdict;
        unsigned int action = 0;

        /* don't bother if Cat-0 error */
        if (ata_eh_categorize_error(eflags, err_mask, &xfer_ok) == 0)
                return 0;

        /* record error and determine whether speed down is necessary */
        ata_ering_record(&dev->ering, eflags, err_mask);
        verdict = ata_eh_speed_down_verdict(dev);

        /* turn off NCQ? */
        if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
            (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
                           ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
                dev->flags |= ATA_DFLAG_NCQ_OFF;
                ata_dev_printk(dev, KERN_WARNING,
                               "NCQ disabled due to excessive errors\n");
                goto done;
        }

        /* speed down? */
        if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
                /* speed down SATA link speed if possible */
                if (sata_down_spd_limit(link) == 0) {
                        action |= ATA_EH_RESET;
                        goto done;
                }

                /* lower transfer mode */
                if (dev->spdn_cnt < 2) {
                        static const int dma_dnxfer_sel[] =
                                { ATA_DNXFER_DMA, ATA_DNXFER_40C };
                        static const int pio_dnxfer_sel[] =
                                { ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
                        int sel;

                        if (dev->xfer_shift != ATA_SHIFT_PIO)
                                sel = dma_dnxfer_sel[dev->spdn_cnt];
                        else
                                sel = pio_dnxfer_sel[dev->spdn_cnt];

                        dev->spdn_cnt++;

                        if (ata_down_xfermask_limit(dev, sel) == 0) {
                                action |= ATA_EH_RESET;
                                goto done;
                        }
                }
        }

        /* Fall back to PIO?  Slowing down to PIO is meaningless for
         * SATA ATA devices.  Consider it only for PATA and SATAPI.
         */
        if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
            (link->ap->cbl != ATA_CBL_SATA || dev->class == ATA_DEV_ATAPI) &&
            (dev->xfer_shift != ATA_SHIFT_PIO)) {
                if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
                        dev->spdn_cnt = 0;
                        action |= ATA_EH_RESET;
                        goto done;
                }
        }

        return 0;
 done:
        /* device has been slowed down, blow error history */
        if (!(verdict & ATA_EH_SPDN_KEEP_ERRORS))
                ata_ering_clear(&dev->ering);
        return action;
}

/**
 *      ata_eh_link_autopsy - analyze error and determine recovery action
 *      @link: host link to perform autopsy on
 *
 *      Analyze why @link failed and determine which recovery actions
 *      are needed.  This function also sets more detailed AC_ERR_*
 *      values and fills sense data for ATAPI CHECK SENSE.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
static void ata_eh_link_autopsy(struct ata_link *link)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        struct ata_device *dev;
        unsigned int all_err_mask = 0, eflags = 0;
        int tag;
        u32 serror;
        int rc;

        DPRINTK("ENTER\n");

        if (ehc->i.flags & ATA_EHI_NO_AUTOPSY)
                return;

        /* obtain and analyze SError */
        rc = sata_scr_read(link, SCR_ERROR, &serror);
        if (rc == 0) {
                ehc->i.serror |= serror;
                ata_eh_analyze_serror(link);
        } else if (rc != -EOPNOTSUPP) {
                /* SError read failed, force reset and probing */
                ehc->i.probe_mask |= ATA_ALL_DEVICES;
                ehc->i.action |= ATA_EH_RESET;
                ehc->i.err_mask |= AC_ERR_OTHER;
        }

        /* analyze NCQ failure */
        ata_eh_analyze_ncq_error(link);

        /* any real error trumps AC_ERR_OTHER */
        if (ehc->i.err_mask & ~AC_ERR_OTHER)
                ehc->i.err_mask &= ~AC_ERR_OTHER;

        all_err_mask |= ehc->i.err_mask;

        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);

                if (!(qc->flags & ATA_QCFLAG_FAILED) ||
                    ata_dev_phys_link(qc->dev) != link)
                        continue;

                /* inherit upper level err_mask */
                qc->err_mask |= ehc->i.err_mask;

                /* analyze TF */
                ehc->i.action |= ata_eh_analyze_tf(qc, &qc->result_tf);

                /* DEV errors are probably spurious in case of ATA_BUS error */
                if (qc->err_mask & AC_ERR_ATA_BUS)
                        qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_MEDIA |
                                          AC_ERR_INVALID);

                /* any real error trumps unknown error */
                if (qc->err_mask & ~AC_ERR_OTHER)
                        qc->err_mask &= ~AC_ERR_OTHER;

                /* SENSE_VALID trumps dev/unknown error and revalidation */
                if (qc->flags & ATA_QCFLAG_SENSE_VALID)
                        qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_OTHER);

                /* determine whether the command is worth retrying */
                if (!(qc->err_mask & AC_ERR_INVALID) &&
                    ((qc->flags & ATA_QCFLAG_IO) || qc->err_mask != AC_ERR_DEV))
                        qc->flags |= ATA_QCFLAG_RETRY;

                /* accumulate error info */
                ehc->i.dev = qc->dev;
                all_err_mask |= qc->err_mask;
                if (qc->flags & ATA_QCFLAG_IO)
                        eflags |= ATA_EFLAG_IS_IO;
        }

        /* enforce default EH actions */
        if (ap->pflags & ATA_PFLAG_FROZEN ||
            all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
                ehc->i.action |= ATA_EH_RESET;
        else if (((eflags & ATA_EFLAG_IS_IO) && all_err_mask) ||
                 (!(eflags & ATA_EFLAG_IS_IO) && (all_err_mask & ~AC_ERR_DEV)))
                ehc->i.action |= ATA_EH_REVALIDATE;

        /* If we have offending qcs and the associated failed device,
         * perform per-dev EH action only on the offending device.
         */
        if (ehc->i.dev) {
                ehc->i.dev_action[ehc->i.dev->devno] |=
                        ehc->i.action & ATA_EH_PERDEV_MASK;
                ehc->i.action &= ~ATA_EH_PERDEV_MASK;
        }

        /* propagate timeout to host link */
        if ((all_err_mask & AC_ERR_TIMEOUT) && !ata_is_host_link(link))
                ap->link.eh_context.i.err_mask |= AC_ERR_TIMEOUT;

        /* record error and consider speeding down */
        dev = ehc->i.dev;
        if (!dev && ((ata_link_max_devices(link) == 1 &&
                      ata_dev_enabled(link->device))))
            dev = link->device;

        if (dev) {
                if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
                        eflags |= ATA_EFLAG_DUBIOUS_XFER;
                ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_eh_autopsy - analyze error and determine recovery action
 *      @ap: host port to perform autopsy on
 *
 *      Analyze all links of @ap and determine why they failed and
 *      which recovery actions are needed.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_eh_autopsy(struct ata_port *ap)
{
        struct ata_link *link;

        ata_for_each_link(link, ap, EDGE)
                ata_eh_link_autopsy(link);

        /* Handle the frigging slave link.  Autopsy is done similarly
         * but actions and flags are transferred over to the master
         * link and handled from there.
         */
        if (ap->slave_link) {
                struct ata_eh_context *mehc = &ap->link.eh_context;
                struct ata_eh_context *sehc = &ap->slave_link->eh_context;

                /* transfer control flags from master to slave */
                sehc->i.flags |= mehc->i.flags & ATA_EHI_TO_SLAVE_MASK;

                /* perform autopsy on the slave link */
                ata_eh_link_autopsy(ap->slave_link);

                /* transfer actions from slave to master and clear slave */
                ata_eh_about_to_do(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
                mehc->i.action          |= sehc->i.action;
                mehc->i.dev_action[1]   |= sehc->i.dev_action[1];
                mehc->i.flags           |= sehc->i.flags;
                ata_eh_done(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
        }

        /* Autopsy of fanout ports can affect host link autopsy.
         * Perform host link autopsy last.
         */
        if (sata_pmp_attached(ap))
                ata_eh_link_autopsy(&ap->link);
}

/**
 *      ata_eh_link_report - report error handling to user
 *      @link: ATA link EH is going on
 *
 *      Report EH to user.
 *
 *      LOCKING:
 *      None.
 */
static void ata_eh_link_report(struct ata_link *link)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        const char *frozen, *desc;
        char tries_buf[6];
        int tag, nr_failed = 0;

        if (ehc->i.flags & ATA_EHI_QUIET)
                return;

        desc = NULL;
        if (ehc->i.desc[0] != '\0')
                desc = ehc->i.desc;

        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);

                if (!(qc->flags & ATA_QCFLAG_FAILED) ||
                    ata_dev_phys_link(qc->dev) != link ||
                    ((qc->flags & ATA_QCFLAG_QUIET) &&
                     qc->err_mask == AC_ERR_DEV))
                        continue;
                if (qc->flags & ATA_QCFLAG_SENSE_VALID && !qc->err_mask)
                        continue;

                nr_failed++;
        }

        if (!nr_failed && !ehc->i.err_mask)
                return;

        frozen = "";
        if (ap->pflags & ATA_PFLAG_FROZEN)
                frozen = " frozen";

        memset(tries_buf, 0, sizeof(tries_buf));
        if (ap->eh_tries < ATA_EH_MAX_TRIES)
                snprintf(tries_buf, sizeof(tries_buf) - 1, " t%d",
                         ap->eh_tries);

        if (ehc->i.dev) {
                ata_dev_printk(ehc->i.dev, KERN_ERR, "exception Emask 0x%x "
                               "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
                               ehc->i.err_mask, link->sactive, ehc->i.serror,
                               ehc->i.action, frozen, tries_buf);
                if (desc)
                        ata_dev_printk(ehc->i.dev, KERN_ERR, "%s\n", desc);
        } else {
                ata_link_printk(link, KERN_ERR, "exception Emask 0x%x "
                                "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
                                ehc->i.err_mask, link->sactive, ehc->i.serror,
                                ehc->i.action, frozen, tries_buf);
                if (desc)
                        ata_link_printk(link, KERN_ERR, "%s\n", desc);
        }

        if (ehc->i.serror)
                ata_link_printk(link, KERN_ERR,
                  "SError: { %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s}\n",
                  ehc->i.serror & SERR_DATA_RECOVERED ? "RecovData " : "",
                  ehc->i.serror & SERR_COMM_RECOVERED ? "RecovComm " : "",
                  ehc->i.serror & SERR_DATA ? "UnrecovData " : "",
                  ehc->i.serror & SERR_PERSISTENT ? "Persist " : "",
                  ehc->i.serror & SERR_PROTOCOL ? "Proto " : "",
                  ehc->i.serror & SERR_INTERNAL ? "HostInt " : "",
                  ehc->i.serror & SERR_PHYRDY_CHG ? "PHYRdyChg " : "",
                  ehc->i.serror & SERR_PHY_INT_ERR ? "PHYInt " : "",
                  ehc->i.serror & SERR_COMM_WAKE ? "CommWake " : "",
                  ehc->i.serror & SERR_10B_8B_ERR ? "10B8B " : "",
                  ehc->i.serror & SERR_DISPARITY ? "Dispar " : "",
                  ehc->i.serror & SERR_CRC ? "BadCRC " : "",
                  ehc->i.serror & SERR_HANDSHAKE ? "Handshk " : "",
                  ehc->i.serror & SERR_LINK_SEQ_ERR ? "LinkSeq " : "",
                  ehc->i.serror & SERR_TRANS_ST_ERROR ? "TrStaTrns " : "",
                  ehc->i.serror & SERR_UNRECOG_FIS ? "UnrecFIS " : "",
                  ehc->i.serror & SERR_DEV_XCHG ? "DevExch " : "");

        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
                struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
                const u8 *cdb = qc->cdb;
                char data_buf[20] = "";
                char cdb_buf[70] = "";

                if (!(qc->flags & ATA_QCFLAG_FAILED) ||
                    ata_dev_phys_link(qc->dev) != link || !qc->err_mask)
                        continue;

                if (qc->dma_dir != DMA_NONE) {
                        static const char *dma_str[] = {
                                [DMA_BIDIRECTIONAL]     = "bidi",
                                [DMA_TO_DEVICE]         = "out",
                                [DMA_FROM_DEVICE]       = "in",
                        };
                        static const char *prot_str[] = {
                                [ATA_PROT_PIO]          = "pio",
                                [ATA_PROT_DMA]          = "dma",
                                [ATA_PROT_NCQ]          = "ncq",
                                [ATAPI_PROT_PIO]        = "pio",
                                [ATAPI_PROT_DMA]        = "dma",
                        };

                        snprintf(data_buf, sizeof(data_buf), " %s %u %s",
                                 prot_str[qc->tf.protocol], qc->nbytes,
                                 dma_str[qc->dma_dir]);
                }

                if (ata_is_atapi(qc->tf.protocol))
                        snprintf(cdb_buf, sizeof(cdb_buf),
                                 "cdb %02x %02x %02x %02x %02x %02x %02x %02x  "
                                 "%02x %02x %02x %02x %02x %02x %02x %02x\n         ",
                                 cdb[0], cdb[1], cdb[2], cdb[3],
                                 cdb[4], cdb[5], cdb[6], cdb[7],
                                 cdb[8], cdb[9], cdb[10], cdb[11],
                                 cdb[12], cdb[13], cdb[14], cdb[15]);

                ata_dev_printk(qc->dev, KERN_ERR,
                        "cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
                        "tag %d%s\n         %s"
                        "res %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
                        "Emask 0x%x (%s)%s\n",
                        cmd->command, cmd->feature, cmd->nsect,
                        cmd->lbal, cmd->lbam, cmd->lbah,
                        cmd->hob_feature, cmd->hob_nsect,
                        cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
                        cmd->device, qc->tag, data_buf, cdb_buf,
                        res->command, res->feature, res->nsect,
                        res->lbal, res->lbam, res->lbah,
                        res->hob_feature, res->hob_nsect,
                        res->hob_lbal, res->hob_lbam, res->hob_lbah,
                        res->device, qc->err_mask, ata_err_string(qc->err_mask),
                        qc->err_mask & AC_ERR_NCQ ? " <F>" : "");

                if (res->command & (ATA_BUSY | ATA_DRDY | ATA_DF | ATA_DRQ |
                                    ATA_ERR)) {
                        if (res->command & ATA_BUSY)
                                ata_dev_printk(qc->dev, KERN_ERR,
                                  "status: { Busy }\n");
                        else
                                ata_dev_printk(qc->dev, KERN_ERR,
                                  "status: { %s%s%s%s}\n",
                                  res->command & ATA_DRDY ? "DRDY " : "",
                                  res->command & ATA_DF ? "DF " : "",
                                  res->command & ATA_DRQ ? "DRQ " : "",
                                  res->command & ATA_ERR ? "ERR " : "");
                }

                if (cmd->command != ATA_CMD_PACKET &&
                    (res->feature & (ATA_ICRC | ATA_UNC | ATA_IDNF |
                                     ATA_ABORTED)))
                        ata_dev_printk(qc->dev, KERN_ERR,
                          "error: { %s%s%s%s}\n",
                          res->feature & ATA_ICRC ? "ICRC " : "",
                          res->feature & ATA_UNC ? "UNC " : "",
                          res->feature & ATA_IDNF ? "IDNF " : "",
                          res->feature & ATA_ABORTED ? "ABRT " : "");
        }
}

/**
 *      ata_eh_report - report error handling to user
 *      @ap: ATA port to report EH about
 *
 *      Report EH to user.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_report(struct ata_port *ap)
{
        struct ata_link *link;

        ata_for_each_link(link, ap, HOST_FIRST)
                ata_eh_link_report(link);
}

static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
                        unsigned int *classes, unsigned long deadline,
                        bool clear_classes)
{
        struct ata_device *dev;

        if (clear_classes)
                ata_for_each_dev(dev, link, ALL)
                        classes[dev->devno] = ATA_DEV_UNKNOWN;

        return reset(link, classes, deadline);
}

static int ata_eh_followup_srst_needed(struct ata_link *link,
                                       int rc, const unsigned int *classes)
{
        if ((link->flags & ATA_LFLAG_NO_SRST) || ata_link_offline(link))
                return 0;
        if (rc == -EAGAIN)
                return 1;
        if (sata_pmp_supported(link->ap) && ata_is_host_link(link))
                return 1;
        return 0;
}

int ata_eh_reset(struct ata_link *link, int classify,
                 ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
                 ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
{
        struct ata_port *ap = link->ap;
        struct ata_link *slave = ap->slave_link;
        struct ata_eh_context *ehc = &link->eh_context;
        struct ata_eh_context *sehc = &slave->eh_context;
        unsigned int *classes = ehc->classes;
        unsigned int lflags = link->flags;
        int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
        int max_tries = 0, try = 0;
        struct ata_link *failed_link;
        struct ata_device *dev;
        unsigned long deadline, now;
        ata_reset_fn_t reset;
        unsigned long flags;
        u32 sstatus;
        int nr_unknown, rc;

        /*
         * Prepare to reset
         */
        while (ata_eh_reset_timeouts[max_tries] != ULONG_MAX)
                max_tries++;
        if (link->flags & ATA_LFLAG_NO_HRST)
                hardreset = NULL;
        if (link->flags & ATA_LFLAG_NO_SRST)
                softreset = NULL;

        /* make sure each reset attemp is at least COOL_DOWN apart */
        if (ehc->i.flags & ATA_EHI_DID_RESET) {
                now = jiffies;
                WARN_ON(time_after(ehc->last_reset, now));
                deadline = ata_deadline(ehc->last_reset,
                                        ATA_EH_RESET_COOL_DOWN);
                if (time_before(now, deadline))
                        schedule_timeout_uninterruptible(deadline - now);
        }

        spin_lock_irqsave(ap->lock, flags);
        ap->pflags |= ATA_PFLAG_RESETTING;
        spin_unlock_irqrestore(ap->lock, flags);

        ata_eh_about_to_do(link, NULL, ATA_EH_RESET);

        ata_for_each_dev(dev, link, ALL) {
                /* If we issue an SRST then an ATA drive (not ATAPI)
                 * may change configuration and be in PIO0 timing. If
                 * we do a hard reset (or are coming from power on)
                 * this is true for ATA or ATAPI. Until we've set a
                 * suitable controller mode we should not touch the
                 * bus as we may be talking too fast.
                 */
                dev->pio_mode = XFER_PIO_0;

                /* If the controller has a pio mode setup function
                 * then use it to set the chipset to rights. Don't
                 * touch the DMA setup as that will be dealt with when
                 * configuring devices.
                 */
                if (ap->ops->set_piomode)
                        ap->ops->set_piomode(ap, dev);
        }

        /* prefer hardreset */
        reset = NULL;
        ehc->i.action &= ~ATA_EH_RESET;
        if (hardreset) {
                reset = hardreset;
                ehc->i.action |= ATA_EH_HARDRESET;
        } else if (softreset) {
                reset = softreset;
                ehc->i.action |= ATA_EH_SOFTRESET;
        }

        if (prereset) {
                unsigned long deadline = ata_deadline(jiffies,
                                                      ATA_EH_PRERESET_TIMEOUT);

                if (slave) {
                        sehc->i.action &= ~ATA_EH_RESET;
                        sehc->i.action |= ehc->i.action;
                }

                rc = prereset(link, deadline);

                /* If present, do prereset on slave link too.  Reset
                 * is skipped iff both master and slave links report
                 * -ENOENT or clear ATA_EH_RESET.
                 */
                if (slave && (rc == 0 || rc == -ENOENT)) {
                        int tmp;

                        tmp = prereset(slave, deadline);
                        if (tmp != -ENOENT)
                                rc = tmp;

                        ehc->i.action |= sehc->i.action;
                }

                if (rc) {
                        if (rc == -ENOENT) {
                                ata_link_printk(link, KERN_DEBUG,
                                                "port disabled. ignoring.\n");
                                ehc->i.action &= ~ATA_EH_RESET;

                                ata_for_each_dev(dev, link, ALL)
                                        classes[dev->devno] = ATA_DEV_NONE;

                                rc = 0;
                        } else
                                ata_link_printk(link, KERN_ERR,
                                        "prereset failed (errno=%d)\n", rc);
                        goto out;
                }

                /* prereset() might have cleared ATA_EH_RESET.  If so,
                 * bang classes and return.
                 */
                if (reset && !(ehc->i.action & ATA_EH_RESET)) {
                        ata_for_each_dev(dev, link, ALL)
                                classes[dev->devno] = ATA_DEV_NONE;
                        rc = 0;
                        goto out;
                }
        }

 retry:
        /*
         * Perform reset
         */
        if (ata_is_host_link(link))
                ata_eh_freeze_port(ap);

        deadline = ata_deadline(jiffies, ata_eh_reset_timeouts[try++]);

        if (reset) {
                if (verbose)
                        ata_link_printk(link, KERN_INFO, "%s resetting link\n",
                                        reset == softreset ? "soft" : "hard");

                /* mark that this EH session started with reset */
                ehc->last_reset = jiffies;
                if (reset == hardreset)
                        ehc->i.flags |= ATA_EHI_DID_HARDRESET;
                else
                        ehc->i.flags |= ATA_EHI_DID_SOFTRESET;

                rc = ata_do_reset(link, reset, classes, deadline, true);
                if (rc && rc != -EAGAIN) {
                        failed_link = link;
                        goto fail;
                }

                /* hardreset slave link if existent */
                if (slave && reset == hardreset) {
                        int tmp;

                        if (verbose)
                                ata_link_printk(slave, KERN_INFO,
                                                "hard resetting link\n");

                        ata_eh_about_to_do(slave, NULL, ATA_EH_RESET);
                        tmp = ata_do_reset(slave, reset, classes, deadline,
                                           false);
                        switch (tmp) {
                        case -EAGAIN:
                                rc = -EAGAIN;
                        case 0:
                                break;
                        default:
                                failed_link = slave;
                                rc = tmp;
                                goto fail;
                        }
                }

                /* perform follow-up SRST if necessary */
                if (reset == hardreset &&
                    ata_eh_followup_srst_needed(link, rc, classes)) {
                        reset = softreset;

                        if (!reset) {
                                ata_link_printk(link, KERN_ERR,
                                                "follow-up softreset required "
                                                "but no softreset avaliable\n");
                                failed_link = link;
                                rc = -EINVAL;
                                goto fail;
                        }

                        ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
                        rc = ata_do_reset(link, reset, classes, deadline, true);
                }
        } else {
                if (verbose)
                        ata_link_printk(link, KERN_INFO, "no reset method "
                                        "available, skipping reset\n");
                if (!(lflags & ATA_LFLAG_ASSUME_CLASS))
                        lflags |= ATA_LFLAG_ASSUME_ATA;
        }

        /*
         * Post-reset processing
         */
        ata_for_each_dev(dev, link, ALL) {
                /* After the reset, the device state is PIO 0 and the
                 * controller state is undefined.  Reset also wakes up
                 * drives from sleeping mode.
                 */
                dev->pio_mode = XFER_PIO_0;
                dev->flags &= ~ATA_DFLAG_SLEEPING;

                if (!ata_phys_link_offline(ata_dev_phys_link(dev))) {
                        /* apply class override */
                        if (lflags & ATA_LFLAG_ASSUME_ATA)
                                classes[dev->devno] = ATA_DEV_ATA;
                        else if (lflags & ATA_LFLAG_ASSUME_SEMB)
                                classes[dev->devno] = ATA_DEV_SEMB_UNSUP;
                } else
                        classes[dev->devno] = ATA_DEV_NONE;
        }

        /* record current link speed */
        if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
                link->sata_spd = (sstatus >> 4) & 0xf;
        if (slave && sata_scr_read(slave, SCR_STATUS, &sstatus) == 0)
                slave->sata_spd = (sstatus >> 4) & 0xf;

        /* thaw the port */
        if (ata_is_host_link(link))
                ata_eh_thaw_port(ap);

        /* postreset() should clear hardware SError.  Although SError
         * is cleared during link resume, clearing SError here is
         * necessary as some PHYs raise hotplug events after SRST.
         * This introduces race condition where hotplug occurs between
         * reset and here.  This race is mediated by cross checking
         * link onlineness and classification result later.
         */
        if (postreset) {
                postreset(link, classes);
                if (slave)
                        postreset(slave, classes);
        }

        /* clear cached SError */
        spin_lock_irqsave(link->ap->lock, flags);
        link->eh_info.serror = 0;
        if (slave)
                slave->eh_info.serror = 0;
        spin_unlock_irqrestore(link->ap->lock, flags);

        /* Make sure onlineness and classification result correspond.
         * Hotplug could have happened during reset and some
         * controllers fail to wait while a drive is spinning up after
         * being hotplugged causing misdetection.  By cross checking
         * link onlineness and classification result, those conditions
         * can be reliably detected and retried.
         */
        nr_unknown = 0;
        ata_for_each_dev(dev, link, ALL) {
                /* convert all ATA_DEV_UNKNOWN to ATA_DEV_NONE */
                if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
                        classes[dev->devno] = ATA_DEV_NONE;
                        if (ata_phys_link_online(ata_dev_phys_link(dev)))
                                nr_unknown++;
                }
        }

        if (classify && nr_unknown) {
                if (try < max_tries) {
                        ata_link_printk(link, KERN_WARNING, "link online but "
                                       "device misclassified, retrying\n");
                        failed_link = link;
                        rc = -EAGAIN;
                        goto fail;
                }
                ata_link_printk(link, KERN_WARNING,
                               "link online but device misclassified, "
                               "device detection might fail\n");
        }

        /* reset successful, schedule revalidation */
        ata_eh_done(link, NULL, ATA_EH_RESET);
        if (slave)
                ata_eh_done(slave, NULL, ATA_EH_RESET);
        ehc->last_reset = jiffies;      /* update to completion time */
        ehc->i.action |= ATA_EH_REVALIDATE;

        rc = 0;
 out:
        /* clear hotplug flag */
        ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
        if (slave)
                sehc->i.flags &= ~ATA_EHI_HOTPLUGGED;

        spin_lock_irqsave(ap->lock, flags);
        ap->pflags &= ~ATA_PFLAG_RESETTING;
        spin_unlock_irqrestore(ap->lock, flags);

        return rc;

 fail:
        /* if SCR isn't accessible on a fan-out port, PMP needs to be reset */
        if (!ata_is_host_link(link) &&
            sata_scr_read(link, SCR_STATUS, &sstatus))
                rc = -ERESTART;

        if (rc == -ERESTART || try >= max_tries)
                goto out;

        now = jiffies;
        if (time_before(now, deadline)) {
                unsigned long delta = deadline - now;

                ata_link_printk(failed_link, KERN_WARNING,
                        "reset failed (errno=%d), retrying in %u secs\n",
                        rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));

                while (delta)
                        delta = schedule_timeout_uninterruptible(delta);
        }

        if (try == max_tries - 1) {
                sata_down_spd_limit(link);
                if (slave)
                        sata_down_spd_limit(slave);
        } else if (rc == -EPIPE)
                sata_down_spd_limit(failed_link);

        if (hardreset)
                reset = hardreset;
        goto retry;
}

static inline void ata_eh_pull_park_action(struct ata_port *ap)
{
        struct ata_link *link;
        struct ata_device *dev;
        unsigned long flags;

        /*
         * This function can be thought of as an extended version of
         * ata_eh_about_to_do() specially crafted to accommodate the
         * requirements of ATA_EH_PARK handling. Since the EH thread
         * does not leave the do {} while () loop in ata_eh_recover as
         * long as the timeout for a park request to *one* device on
         * the port has not expired, and since we still want to pick
         * up park requests to other devices on the same port or
         * timeout updates for the same device, we have to pull
         * ATA_EH_PARK actions from eh_info into eh_context.i
         * ourselves at the beginning of each pass over the loop.
         *
         * Additionally, all write accesses to &ap->park_req_pending
         * through INIT_COMPLETION() (see below) or complete_all()
         * (see ata_scsi_park_store()) are protected by the host lock.
         * As a result we have that park_req_pending.done is zero on
         * exit from this function, i.e. when ATA_EH_PARK actions for
         * *all* devices on port ap have been pulled into the
         * respective eh_context structs. If, and only if,
         * park_req_pending.done is non-zero by the time we reach
         * wait_for_completion_timeout(), another ATA_EH_PARK action
         * has been scheduled for at least one of the devices on port
         * ap and we have to cycle over the do {} while () loop in
         * ata_eh_recover() again.
         */

        spin_lock_irqsave(ap->lock, flags);
        INIT_COMPLETION(ap->park_req_pending);
        ata_for_each_link(link, ap, EDGE) {
                ata_for_each_dev(dev, link, ALL) {
                        struct ata_eh_info *ehi = &link->eh_info;

                        link->eh_context.i.dev_action[dev->devno] |=
                                ehi->dev_action[dev->devno] & ATA_EH_PARK;
                        ata_eh_clear_action(link, dev, ehi, ATA_EH_PARK);
                }
        }
        spin_unlock_irqrestore(ap->lock, flags);
}

static void ata_eh_park_issue_cmd(struct ata_device *dev, int park)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;
        struct ata_taskfile tf;
        unsigned int err_mask;

        ata_tf_init(dev, &tf);
        if (park) {
                ehc->unloaded_mask |= 1 << dev->devno;
                tf.command = ATA_CMD_IDLEIMMEDIATE;
                tf.feature = 0x44;
                tf.lbal = 0x4c;
                tf.lbam = 0x4e;
                tf.lbah = 0x55;
        } else {
                ehc->unloaded_mask &= ~(1 << dev->devno);
                tf.command = ATA_CMD_CHK_POWER;
        }

        tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
        tf.protocol |= ATA_PROT_NODATA;
        err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
        if (park && (err_mask || tf.lbal != 0xc4)) {
                ata_dev_printk(dev, KERN_ERR, "head unload failed!\n");
                ehc->unloaded_mask &= ~(1 << dev->devno);
        }
}

static int ata_eh_revalidate_and_attach(struct ata_link *link,
                                        struct ata_device **r_failed_dev)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        struct ata_device *dev;
        unsigned int new_mask = 0;
        unsigned long flags;
        int rc = 0;

        DPRINTK("ENTER\n");

        /* For PATA drive side cable detection to work, IDENTIFY must
         * be done backwards such that PDIAG- is released by the slave
         * device before the master device is identified.
         */
        ata_for_each_dev(dev, link, ALL_REVERSE) {
                unsigned int action = ata_eh_dev_action(dev);
                unsigned int readid_flags = 0;

                if (ehc->i.flags & ATA_EHI_DID_RESET)
                        readid_flags |= ATA_READID_POSTRESET;

                if ((action & ATA_EH_REVALIDATE) && ata_dev_enabled(dev)) {
                        WARN_ON(dev->class == ATA_DEV_PMP);

                        if (ata_phys_link_offline(ata_dev_phys_link(dev))) {
                                rc = -EIO;
                                goto err;
                        }

                        ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
                        rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
                                                readid_flags);
                        if (rc)
                                goto err;

                        ata_eh_done(link, dev, ATA_EH_REVALIDATE);

                        /* Configuration may have changed, reconfigure
                         * transfer mode.
                         */
                        ehc->i.flags |= ATA_EHI_SETMODE;

                        /* schedule the scsi_rescan_device() here */
                        queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
                } else if (dev->class == ATA_DEV_UNKNOWN &&
                           ehc->tries[dev->devno] &&
                           ata_class_enabled(ehc->classes[dev->devno])) {
                        dev->class = ehc->classes[dev->devno];

                        if (dev->class == ATA_DEV_PMP)
                                rc = sata_pmp_attach(dev);
                        else
                                rc = ata_dev_read_id(dev, &dev->class,
                                                     readid_flags, dev->id);
                        switch (rc) {
                        case 0:
                                new_mask |= 1 << dev->devno;
                                break;
                        case -ENOENT:
                                /* IDENTIFY was issued to non-existent
                                 * device.  No need to reset.  Just
                                 * thaw and kill the device.
                                 */
                                ata_eh_thaw_port(ap);
                                dev->class = ATA_DEV_UNKNOWN;
                                break;
                        default:
                                dev->class = ATA_DEV_UNKNOWN;
                                goto err;
                        }
                }
        }

        /* PDIAG- should have been released, ask cable type if post-reset */
        if ((ehc->i.flags & ATA_EHI_DID_RESET) && ata_is_host_link(link)) {
                if (ap->ops->cable_detect)
                        ap->cbl = ap->ops->cable_detect(ap);
                ata_force_cbl(ap);
        }

        /* Configure new devices forward such that user doesn't see
         * device detection messages backwards.
         */
        ata_for_each_dev(dev, link, ALL) {
                if (!(new_mask & (1 << dev->devno)) ||
                    dev->class == ATA_DEV_PMP)
                        continue;

                ehc->i.flags |= ATA_EHI_PRINTINFO;
                rc = ata_dev_configure(dev);
                ehc->i.flags &= ~ATA_EHI_PRINTINFO;
                if (rc)
                        goto err;

                spin_lock_irqsave(ap->lock, flags);
                ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
                spin_unlock_irqrestore(ap->lock, flags);

                /* new device discovered, configure xfermode */
                ehc->i.flags |= ATA_EHI_SETMODE;
        }

        return 0;

 err:
        *r_failed_dev = dev;
        DPRINTK("EXIT rc=%d\n", rc);
        return rc;
}

/**
 *      ata_set_mode - Program timings and issue SET FEATURES - XFER
 *      @link: link on which timings will be programmed
 *      @r_failed_dev: out paramter for failed device
 *
 *      Set ATA device disk transfer mode (PIO3, UDMA6, etc.).  If
 *      ata_set_mode() fails, pointer to the failing device is
 *      returned in @r_failed_dev.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      0 on success, negative errno otherwise
 */
int ata_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
{
        struct ata_port *ap = link->ap;
        struct ata_device *dev;
        int rc;

        /* if data transfer is verified, clear DUBIOUS_XFER on ering top */
        ata_for_each_dev(dev, link, ENABLED) {
                if (!(dev->flags & ATA_DFLAG_DUBIOUS_XFER)) {
                        struct ata_ering_entry *ent;

                        ent = ata_ering_top(&dev->ering);
                        if (ent)
                                ent->eflags &= ~ATA_EFLAG_DUBIOUS_XFER;
                }
        }

        /* has private set_mode? */
        if (ap->ops->set_mode)
                rc = ap->ops->set_mode(link, r_failed_dev);
        else
                rc = ata_do_set_mode(link, r_failed_dev);

        /* if transfer mode has changed, set DUBIOUS_XFER on device */
        ata_for_each_dev(dev, link, ENABLED) {
                struct ata_eh_context *ehc = &link->eh_context;
                u8 saved_xfer_mode = ehc->saved_xfer_mode[dev->devno];
                u8 saved_ncq = !!(ehc->saved_ncq_enabled & (1 << dev->devno));

                if (dev->xfer_mode != saved_xfer_mode ||
                    ata_ncq_enabled(dev) != saved_ncq)
                        dev->flags |= ATA_DFLAG_DUBIOUS_XFER;
        }

        return rc;
}

/**
 *      atapi_eh_clear_ua - Clear ATAPI UNIT ATTENTION after reset
 *      @dev: ATAPI device to clear UA for
 *
 *      Resets and other operations can make an ATAPI device raise
 *      UNIT ATTENTION which causes the next operation to fail.  This
 *      function clears UA.
 *
 *      LOCKING:
 *      EH context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */
static int atapi_eh_clear_ua(struct ata_device *dev)
{
        int i;

        for (i = 0; i < ATA_EH_UA_TRIES; i++) {
                u8 sense_buffer[SCSI_SENSE_BUFFERSIZE];
                u8 sense_key = 0;
                unsigned int err_mask;

                err_mask = atapi_eh_tur(dev, &sense_key);
                if (err_mask != 0 && err_mask != AC_ERR_DEV) {
                        ata_dev_printk(dev, KERN_WARNING, "TEST_UNIT_READY "
                                "failed (err_mask=0x%x)\n", err_mask);
                        return -EIO;
                }

                if (!err_mask || sense_key != UNIT_ATTENTION)
                        return 0;

                err_mask = atapi_eh_request_sense(dev, sense_buffer, sense_key);
                if (err_mask) {
                        ata_dev_printk(dev, KERN_WARNING, "failed to clear "
                                "UNIT ATTENTION (err_mask=0x%x)\n", err_mask);
                        return -EIO;
                }
        }

        ata_dev_printk(dev, KERN_WARNING,
                "UNIT ATTENTION persists after %d tries\n", ATA_EH_UA_TRIES);

        return 0;
}

static int ata_link_nr_enabled(struct ata_link *link)
{
        struct ata_device *dev;
        int cnt = 0;

        ata_for_each_dev(dev, link, ENABLED)
                cnt++;
        return cnt;
}

static int ata_link_nr_vacant(struct ata_link *link)
{
        struct ata_device *dev;
        int cnt = 0;

        ata_for_each_dev(dev, link, ALL)
                if (dev->class == ATA_DEV_UNKNOWN)
                        cnt++;
        return cnt;
}

static int ata_eh_skip_recovery(struct ata_link *link)
{
        struct ata_port *ap = link->ap;
        struct ata_eh_context *ehc = &link->eh_context;
        struct ata_device *dev;

        /* skip disabled links */
        if (link->flags & ATA_LFLAG_DISABLED)
                return 1;

        /* thaw frozen port and recover failed devices */
        if ((ap->pflags & ATA_PFLAG_FROZEN) || ata_link_nr_enabled(link))
                return 0;

        /* reset at least once if reset is requested */
        if ((ehc->i.action & ATA_EH_RESET) &&
            !(ehc->i.flags & ATA_EHI_DID_RESET))
                return 0;

        /* skip if class codes for all vacant slots are ATA_DEV_NONE */
        ata_for_each_dev(dev, link, ALL) {
                if (dev->class == ATA_DEV_UNKNOWN &&
                    ehc->classes[dev->devno] != ATA_DEV_NONE)
                        return 0;
        }

        return 1;
}

static int ata_eh_schedule_probe(struct ata_device *dev)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;

        if (!(ehc->i.probe_mask & (1 << dev->devno)) ||
            (ehc->did_probe_mask & (1 << dev->devno)))
                return 0;

        ata_eh_detach_dev(dev);
        ata_dev_init(dev);
        ehc->did_probe_mask |= (1 << dev->devno);
        ehc->i.action |= ATA_EH_RESET;
        ehc->saved_xfer_mode[dev->devno] = 0;
        ehc->saved_ncq_enabled &= ~(1 << dev->devno);

        return 1;
}

static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
{
        struct ata_eh_context *ehc = &dev->link->eh_context;

        ehc->tries[dev->devno]--;

        switch (err) {
        case -ENODEV:
                /* device missing or wrong IDENTIFY data, schedule probing */
                ehc->i.probe_mask |= (1 << dev->devno);
        case -EINVAL:
                /* give it just one more chance */
                ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
        case -EIO:
                if (ehc->tries[dev->devno] == 1 && dev->pio_mode > XFER_PIO_0) {
                        /* This is the last chance, better to slow
                         * down than lose it.
                         */
                        sata_down_spd_limit(ata_dev_phys_link(dev));
                        ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
                }
        }

        if (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {
                /* disable device if it has used up all its chances */
                ata_dev_disable(dev);

                /* detach if offline */
                if (ata_phys_link_offline(ata_dev_phys_link(dev)))
                        ata_eh_detach_dev(dev);

                /* schedule probe if necessary */
                if (ata_eh_schedule_probe(dev)) {
                        ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
                        memset(ehc->cmd_timeout_idx[dev->devno], 0,
                               sizeof(ehc->cmd_timeout_idx[dev->devno]));
                }

                return 1;
        } else {
                ehc->i.action |= ATA_EH_RESET;
                return 0;
        }
}

/**
 *      ata_eh_recover - recover host port after error
 *      @ap: host port to recover
 *      @prereset: prereset method (can be NULL)
 *      @softreset: softreset method (can be NULL)
 *      @hardreset: hardreset method (can be NULL)
 *      @postreset: postreset method (can be NULL)
 *      @r_failed_link: out parameter for failed link
 *
 *      This is the alpha and omega, eum and yang, heart and soul of
 *      libata exception handling.  On entry, actions required to
 *      recover each link and hotplug requests are recorded in the
 *      link's eh_context.  This function executes all the operations
 *      with appropriate retrials and fallbacks to resurrect failed
 *      devices, detach goners and greet newcomers.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */
int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
                   ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
                   ata_postreset_fn_t postreset,
                   struct ata_link **r_failed_link)
{
        struct ata_link *link;
        struct ata_device *dev;
        int nr_failed_devs;
        int rc;
        unsigned long flags, deadline;

        DPRINTK("ENTER\n");

        /* prep for recovery */
        ata_for_each_link(link, ap, EDGE) {
                struct ata_eh_context *ehc = &link->eh_context;

                /* re-enable link? */
                if (ehc->i.action & ATA_EH_ENABLE_LINK) {
                        ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
                        spin_lock_irqsave(ap->lock, flags);
                        link->flags &= ~ATA_LFLAG_DISABLED;
                        spin_unlock_irqrestore(ap->lock, flags);
                        ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
                }

                ata_for_each_dev(dev, link, ALL) {
                        if (link->flags & ATA_LFLAG_NO_RETRY)
                                ehc->tries[dev->devno] = 1;
                        else
                                ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;

                        /* collect port action mask recorded in dev actions */
                        ehc->i.action |= ehc->i.dev_action[dev->devno] &
                                         ~ATA_EH_PERDEV_MASK;
                        ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;

                        /* process hotplug request */
                        if (dev->flags & ATA_DFLAG_DETACH)
                                ata_eh_detach_dev(dev);

                        /* schedule probe if necessary */
                        if (!ata_dev_enabled(dev))
                                ata_eh_schedule_probe(dev);
                }
        }

 retry:
        rc = 0;
        nr_failed_devs = 0;

        /* if UNLOADING, finish immediately */
        if (ap->pflags & ATA_PFLAG_UNLOADING)
                goto out;

        /* prep for EH */
        ata_for_each_link(link, ap, EDGE) {
                struct ata_eh_context *ehc = &link->eh_context;

                /* skip EH if possible. */
                if (ata_eh_skip_recovery(link))
                        ehc->i.action = 0;

                ata_for_each_dev(dev, link, ALL)
                        ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
        }

        /* reset */
        ata_for_each_link(link, ap, EDGE) {
                struct ata_eh_context *ehc = &link->eh_context;

                if (!(ehc->i.action & ATA_EH_RESET))
                        continue;

                rc = ata_eh_reset(link, ata_link_nr_vacant(link),
                                  prereset, softreset, hardreset, postreset);
                if (rc) {
                        ata_link_printk(link, KERN_ERR,
                                        "reset failed, giving up\n");
                        goto out;
                }
        }

        do {
                unsigned long now;

                /*
                 * clears ATA_EH_PARK in eh_info and resets
                 * ap->park_req_pending
                 */
                ata_eh_pull_park_action(ap);

                deadline = jiffies;
                ata_for_each_link(link, ap, EDGE) {
                        ata_for_each_dev(dev, link, ALL) {
                                struct ata_eh_context *ehc = &link->eh_context;
                                unsigned long tmp;

                                if (dev->class != ATA_DEV_ATA)
                                        continue;
                                if (!(ehc->i.dev_action[dev->devno] &
                                      ATA_EH_PARK))
                                        continue;
                                tmp = dev->unpark_deadline;
                                if (time_before(deadline, tmp))
                                        deadline = tmp;
                                else if (time_before_eq(tmp, jiffies))
                                        continue;
                                if (ehc->unloaded_mask & (1 << dev->devno))
                                        continue;

                                ata_eh_park_issue_cmd(dev, 1);
                        }
                }

                now = jiffies;
                if (time_before_eq(deadline, now))
                        break;

                deadline = wait_for_completion_timeout(&ap->park_req_pending,
                                                       deadline - now);
        } while (deadline);
        ata_for_each_link(link, ap, EDGE) {
                ata_for_each_dev(dev, link, ALL) {
                        if (!(link->eh_context.unloaded_mask &
                              (1 << dev->devno)))
                                continue;

                        ata_eh_park_issue_cmd(dev, 0);
                        ata_eh_done(link, dev, ATA_EH_PARK);
                }
        }

        /* the rest */
        ata_for_each_link(link, ap, EDGE) {
                struct ata_eh_context *ehc = &link->eh_context;

                /* revalidate existing devices and attach new ones */
                rc = ata_eh_revalidate_and_attach(link, &dev);
                if (rc)
                        goto dev_fail;

                /* if PMP got attached, return, pmp EH will take care of it */
                if (link->device->class == ATA_DEV_PMP) {
                        ehc->i.action = 0;
                        return 0;
                }

                /* configure transfer mode if necessary */
                if (ehc->i.flags & ATA_EHI_SETMODE) {
                        rc = ata_set_mode(link, &dev);
                        if (rc)
                                goto dev_fail;
                        ehc->i.flags &= ~ATA_EHI_SETMODE;
                }

                /* If reset has been issued, clear UA to avoid
                 * disrupting the current users of the device.
                 */
                if (ehc->i.flags & ATA_EHI_DID_RESET) {
                        ata_for_each_dev(dev, link, ALL) {
                                if (dev->class != ATA_DEV_ATAPI)
                                        continue;
                                rc = atapi_eh_clear_ua(dev);
                                if (rc)
                                        goto dev_fail;
                        }
                }

                /* configure link power saving */
                if (ehc->i.action & ATA_EH_LPM)
                        ata_for_each_dev(dev, link, ALL)
                                ata_dev_enable_pm(dev, ap->pm_policy);

                /* this link is okay now */
                ehc->i.flags = 0;
                continue;

dev_fail:
                nr_failed_devs++;
                ata_eh_handle_dev_fail(dev, rc);

                if (ap->pflags & ATA_PFLAG_FROZEN) {
                        /* PMP reset requires working host port.
                         * Can't retry if it's frozen.
                         */
                        if (sata_pmp_attached(ap))
                                goto out;
                        break;
                }
        }

        if (nr_failed_devs)
                goto retry;

 out:
        if (rc && r_failed_link)
                *r_failed_link = link;

        DPRINTK("EXIT, rc=%d\n", rc);
        return rc;
}

/**
 *      ata_eh_finish - finish up EH
 *      @ap: host port to finish EH for
 *
 *      Recovery is complete.  Clean up EH states and retry or finish
 *      failed qcs.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_finish(struct ata_port *ap)
{
        int tag;

        /* retry or finish qcs */
        for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
                struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);

                if (!(qc->flags & ATA_QCFLAG_FAILED))
                        continue;

                if (qc->err_mask) {
                        /* FIXME: Once EH migration is complete,
                         * generate sense data in this function,
                         * considering both err_mask and tf.
                         */
                        if (qc->flags & ATA_QCFLAG_RETRY)
                                ata_eh_qc_retry(qc);
                        else
                                ata_eh_qc_complete(qc);
                } else {
                        if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
                                ata_eh_qc_complete(qc);
                        } else {
                                /* feed zero TF to sense generation */
                                memset(&qc->result_tf, 0, sizeof(qc->result_tf));
                                ata_eh_qc_retry(qc);
                        }
                }
        }

        /* make sure nr_active_links is zero after EH */
        WARN_ON(ap->nr_active_links);
        ap->nr_active_links = 0;
}

/**
 *      ata_do_eh - do standard error handling
 *      @ap: host port to handle error for
 *
 *      @prereset: prereset method (can be NULL)
 *      @softreset: softreset method (can be NULL)
 *      @hardreset: hardreset method (can be NULL)
 *      @postreset: postreset method (can be NULL)
 *
 *      Perform standard error handling sequence.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
               ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
               ata_postreset_fn_t postreset)
{
        struct ata_device *dev;
        int rc;

        ata_eh_autopsy(ap);
        ata_eh_report(ap);

        rc = ata_eh_recover(ap, prereset, softreset, hardreset, postreset,
                            NULL);
        if (rc) {
                ata_for_each_dev(dev, &ap->link, ALL)
                        ata_dev_disable(dev);
        }

        ata_eh_finish(ap);
}

/**
 *      ata_std_error_handler - standard error handler
 *      @ap: host port to handle error for
 *
 *      Standard error handler
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_std_error_handler(struct ata_port *ap)
{
        struct ata_port_operations *ops = ap->ops;
        ata_reset_fn_t hardreset = ops->hardreset;

        /* ignore built-in hardreset if SCR access is not available */
        if (ata_is_builtin_hardreset(hardreset) && !sata_scr_valid(&ap->link))
                hardreset = NULL;

        ata_do_eh(ap, ops->prereset, ops->softreset, hardreset, ops->postreset);
}

#ifdef CONFIG_PM
/**
 *      ata_eh_handle_port_suspend - perform port suspend operation
 *      @ap: port to suspend
 *
 *      Suspend @ap.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
static void ata_eh_handle_port_suspend(struct ata_port *ap)
{
        unsigned long flags;
        int rc = 0;

        /* are we suspending? */
        spin_lock_irqsave(ap->lock, flags);
        if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
            ap->pm_mesg.event == PM_EVENT_ON) {
                spin_unlock_irqrestore(ap->lock, flags);
                return;
        }
        spin_unlock_irqrestore(ap->lock, flags);

        WARN_ON(ap->pflags & ATA_PFLAG_SUSPENDED);

        /* tell ACPI we're suspending */
        rc = ata_acpi_on_suspend(ap);
        if (rc)
                goto out;

        /* suspend */
        ata_eh_freeze_port(ap);

        if (ap->ops->port_suspend)
                rc = ap->ops->port_suspend(ap, ap->pm_mesg);

        ata_acpi_set_state(ap, PMSG_SUSPEND);
 out:
        /* report result */
        spin_lock_irqsave(ap->lock, flags);

        ap->pflags &= ~ATA_PFLAG_PM_PENDING;
        if (rc == 0)
                ap->pflags |= ATA_PFLAG_SUSPENDED;
        else if (ap->pflags & ATA_PFLAG_FROZEN)
                ata_port_schedule_eh(ap);

        if (ap->pm_result) {
                *ap->pm_result = rc;
                ap->pm_result = NULL;
        }

        spin_unlock_irqrestore(ap->lock, flags);

        return;
}

/**
 *      ata_eh_handle_port_resume - perform port resume operation
 *      @ap: port to resume
 *
 *      Resume @ap.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
static void ata_eh_handle_port_resume(struct ata_port *ap)
{
        unsigned long flags;
        int rc = 0;

        /* are we resuming? */
        spin_lock_irqsave(ap->lock, flags);
        if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
            ap->pm_mesg.event != PM_EVENT_ON) {
                spin_unlock_irqrestore(ap->lock, flags);
                return;
        }
        spin_unlock_irqrestore(ap->lock, flags);

        WARN_ON(!(ap->pflags & ATA_PFLAG_SUSPENDED));

        ata_acpi_set_state(ap, PMSG_ON);

        if (ap->ops->port_resume)
                rc = ap->ops->port_resume(ap);

        /* tell ACPI that we're resuming */
        ata_acpi_on_resume(ap);

        /* report result */
        spin_lock_irqsave(ap->lock, flags);
        ap->pflags &= ~(ATA_PFLAG_PM_PENDING | ATA_PFLAG_SUSPENDED);
        if (ap->pm_result) {
                *ap->pm_result = rc;
                ap->pm_result = NULL;
        }
        spin_unlock_irqrestore(ap->lock, flags);
}
#endif /* CONFIG_PM */