libata: don't check whether to use DMA or not for no data commands

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

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 2e6e1622dc6d0b61566a7224612d2c834b395da3..57a43649a4616bf0cdaeb9614d8489e3dbbb9758 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2343,8 +2343,8 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
 {
        struct scsi_cmnd *scmd = qc->scsicmd;
        struct ata_device *dev = qc->dev;
-       int using_pio = (dev->flags & ATA_DFLAG_PIO);
        int nodata = (scmd->sc_data_direction == DMA_NONE);
+       int using_pio = !nodata && (dev->flags & ATA_DFLAG_PIO);
        unsigned int nbytes;
 
        memset(qc->cdb, 0, dev->cdb_len);
@@ -2362,7 +2362,7 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
        ata_qc_set_pc_nbytes(qc);
 
        /* check whether ATAPI DMA is safe */
-       if (!using_pio && ata_check_atapi_dma(qc))
+       if (!nodata && !using_pio && atapi_check_dma(qc))
                using_pio = 1;
 
        /* Some controller variants snoop this value for Packet
@@ -2402,13 +2402,11 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
        qc->tf.lbam = (nbytes & 0xFF);
        qc->tf.lbah = (nbytes >> 8);
 
-       if (using_pio || nodata) {
-               /* no data, or PIO data xfer */
-               if (nodata)
-                       qc->tf.protocol = ATAPI_PROT_NODATA;
-               else
-                       qc->tf.protocol = ATAPI_PROT_PIO;
-       } else {
+       if (nodata)
+               qc->tf.protocol = ATAPI_PROT_NODATA;
+       else if (using_pio)
+               qc->tf.protocol = ATAPI_PROT_PIO;
+       else {
                /* DMA data xfer */
                qc->tf.protocol = ATAPI_PROT_DMA;
                qc->tf.feature |= ATAPI_PKT_DMA;