drivers/media/video/cx18/cx18-streams.c

   1 /*
   2  *  cx18 init/start/stop/exit stream functions
   3  *
   4  *  Derived from ivtv-streams.c
   5  *
   6  *  Copyright (C) 2007  Hans Verkuil <hverkuil@xs4all.nl>
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21  *  02111-1307  USA
  22  */
  23
  24 #include "cx18-driver.h"
  25 #include "cx18-fileops.h"
  26 #include "cx18-mailbox.h"
  27 #include "cx18-i2c.h"
  28 #include "cx18-queue.h"
  29 #include "cx18-ioctl.h"
  30 #include "cx18-streams.h"
  31 #include "cx18-cards.h"
  32 #include "cx18-scb.h"
  33 #include "cx18-av-core.h"
  34 #include "cx18-dvb.h"
  35
  36 #define CX18_DSP0_INTERRUPT_MASK        0xd0004C
  37
  38 static struct file_operations cx18_v4l2_enc_fops = {
  39         .owner = THIS_MODULE,
  40         .read = cx18_v4l2_read,
  41         .open = cx18_v4l2_open,
  42         /* FIXME change to video_ioctl2 if serialization lock can be removed */
  43         .ioctl = cx18_v4l2_ioctl,
  44         .compat_ioctl = v4l_compat_ioctl32,
  45         .release = cx18_v4l2_close,
  46         .poll = cx18_v4l2_enc_poll,
  47 };
  48
  49 /* offset from 0 to register ts v4l2 minors on */
  50 #define CX18_V4L2_ENC_TS_OFFSET   16
  51 /* offset from 0 to register pcm v4l2 minors on */
  52 #define CX18_V4L2_ENC_PCM_OFFSET  24
  53 /* offset from 0 to register yuv v4l2 minors on */
  54 #define CX18_V4L2_ENC_YUV_OFFSET  32
  55
  56 static struct {
  57         const char *name;
  58         int vfl_type;
  59         int minor_offset;
  60         int dma;
  61         enum v4l2_buf_type buf_type;
  62         struct file_operations *fops;
  63 } cx18_stream_info[] = {
  64         {       /* CX18_ENC_STREAM_TYPE_MPG */
  65                 "encoder MPEG",
  66                 VFL_TYPE_GRABBER, 0,
  67                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_VIDEO_CAPTURE,
  68                 &cx18_v4l2_enc_fops
  69         },
  70         {       /* CX18_ENC_STREAM_TYPE_TS */
  71                 "TS",
  72                 VFL_TYPE_GRABBER, -1,
  73                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_VIDEO_CAPTURE,
  74                 &cx18_v4l2_enc_fops
  75         },
  76         {       /* CX18_ENC_STREAM_TYPE_YUV */
  77                 "encoder YUV",
  78                 VFL_TYPE_GRABBER, CX18_V4L2_ENC_YUV_OFFSET,
  79                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_VIDEO_CAPTURE,
  80                 &cx18_v4l2_enc_fops
  81         },
  82         {       /* CX18_ENC_STREAM_TYPE_VBI */
  83                 "encoder VBI",
  84                 VFL_TYPE_VBI, 0,
  85                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_VBI_CAPTURE,
  86                 &cx18_v4l2_enc_fops
  87         },
  88         {       /* CX18_ENC_STREAM_TYPE_PCM */
  89                 "encoder PCM audio",
  90                 VFL_TYPE_GRABBER, CX18_V4L2_ENC_PCM_OFFSET,
  91                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_PRIVATE,
  92                 &cx18_v4l2_enc_fops
  93         },
  94         {       /* CX18_ENC_STREAM_TYPE_IDX */
  95                 "encoder IDX",
  96                 VFL_TYPE_GRABBER, -1,
  97                 PCI_DMA_FROMDEVICE, V4L2_BUF_TYPE_VIDEO_CAPTURE,
  98                 &cx18_v4l2_enc_fops
  99         },
 100         {       /* CX18_ENC_STREAM_TYPE_RAD */
 101                 "encoder radio",
 102                 VFL_TYPE_RADIO, 0,
 103                 PCI_DMA_NONE, V4L2_BUF_TYPE_PRIVATE,
 104                 &cx18_v4l2_enc_fops
 105         },
 106 };
 107
 108 static void cx18_stream_init(struct cx18 *cx, int type)
 109 {
 110         struct cx18_stream *s = &cx->streams[type];
 111         struct video_device *dev = s->v4l2dev;
 112         u32 max_size = cx->options.megabytes[type] * 1024 * 1024;
 113
 114         /* we need to keep v4l2dev, so restore it afterwards */
 115         memset(s, 0, sizeof(*s));
 116         s->v4l2dev = dev;
 117
 118         /* initialize cx18_stream fields */
 119         s->cx = cx;
 120         s->type = type;
 121         s->name = cx18_stream_info[type].name;
 122         s->handle = 0xffffffff;
 123
 124         s->dma = cx18_stream_info[type].dma;
 125         s->buf_size = cx->stream_buf_size[type];
 126         if (s->buf_size)
 127                 s->buffers = max_size / s->buf_size;
 128         if (s->buffers > 63) {
 129                 /* Each stream has a maximum of 63 buffers,
 130                    ensure we do not exceed that. */
 131                 s->buffers = 63;
 132                 s->buf_size = (max_size / s->buffers) & ~0xfff;
 133         }
 134         spin_lock_init(&s->qlock);
 135         init_waitqueue_head(&s->waitq);
 136         s->id = -1;
 137         cx18_queue_init(&s->q_free);
 138         cx18_queue_init(&s->q_full);
 139         cx18_queue_init(&s->q_io);
 140 }
 141
 142 static int cx18_prep_dev(struct cx18 *cx, int type)
 143 {
 144         struct cx18_stream *s = &cx->streams[type];
 145         u32 cap = cx->v4l2_cap;
 146         int minor_offset = cx18_stream_info[type].minor_offset;
 147         int minor;
 148
 149         /* These four fields are always initialized. If v4l2dev == NULL, then
 150            this stream is not in use. In that case no other fields but these
 151            four can be used. */
 152         s->v4l2dev = NULL;
 153         s->cx = cx;
 154         s->type = type;
 155         s->name = cx18_stream_info[type].name;
 156
 157         /* Check whether the radio is supported */
 158         if (type == CX18_ENC_STREAM_TYPE_RAD && !(cap & V4L2_CAP_RADIO))
 159                 return 0;
 160
 161         /* Check whether VBI is supported */
 162         if (type == CX18_ENC_STREAM_TYPE_VBI &&
 163             !(cap & (V4L2_CAP_VBI_CAPTURE | V4L2_CAP_SLICED_VBI_CAPTURE)))
 164                 return 0;
 165
 166         /* card number + user defined offset + device offset */
 167         minor = cx->num + cx18_first_minor + minor_offset;
 168
 169         /* User explicitly selected 0 buffers for these streams, so don't
 170            create them. */
 171         if (cx18_stream_info[type].dma != PCI_DMA_NONE &&
 172             cx->options.megabytes[type] == 0) {
 173                 CX18_INFO("Disabled %s device\n", cx18_stream_info[type].name);
 174                 return 0;
 175         }
 176
 177         cx18_stream_init(cx, type);
 178
 179         if (minor_offset == -1)
 180                 return 0;
 181
 182         /* allocate and initialize the v4l2 video device structure */
 183         s->v4l2dev = video_device_alloc();
 184         if (s->v4l2dev == NULL) {
 185                 CX18_ERR("Couldn't allocate v4l2 video_device for %s\n",
 186                                 s->name);
 187                 return -ENOMEM;
 188         }
 189
 190         snprintf(s->v4l2dev->name, sizeof(s->v4l2dev->name), "cx18-%d",
 191                         cx->num);
 192
 193         s->v4l2dev->minor = minor;
 194         s->v4l2dev->parent = &cx->dev->dev;
 195         s->v4l2dev->fops = cx18_stream_info[type].fops;
 196         s->v4l2dev->release = video_device_release;
 197         s->v4l2dev->tvnorms = V4L2_STD_ALL;
 198         cx18_set_funcs(s->v4l2dev);
 199         return 0;
 200 }
 201
 202 /* Initialize v4l2 variables and register v4l2 devices */
 203 int cx18_streams_setup(struct cx18 *cx)
 204 {
 205         int type;
 206
 207         /* Setup V4L2 Devices */
 208         for (type = 0; type < CX18_MAX_STREAMS; type++) {
 209                 /* Prepare device */
 210                 if (cx18_prep_dev(cx, type))
 211                         break;
 212
 213                 /* Allocate Stream */
 214                 if (cx18_stream_alloc(&cx->streams[type]))
 215                         break;
 216         }
 217         if (type == CX18_MAX_STREAMS)
 218                 return 0;
 219
 220         /* One or more streams could not be initialized. Clean 'em all up. */
 221         cx18_streams_cleanup(cx, 0);
 222         return -ENOMEM;
 223 }
 224
 225 static int cx18_reg_dev(struct cx18 *cx, int type)
 226 {
 227         struct cx18_stream *s = &cx->streams[type];
 228         int vfl_type = cx18_stream_info[type].vfl_type;
 229         int minor;
 230
 231         /* TODO: Shouldn't this be a VFL_TYPE_TRANSPORT or something?
 232          * We need a VFL_TYPE_TS defined.
 233          */
 234         if (strcmp("TS", s->name) == 0) {
 235                 /* just return if no DVB is supported */
 236                 if ((cx->card->hw_all & CX18_HW_DVB) == 0)
 237                         return 0;
 238                 if (cx18_dvb_register(s) < 0) {
 239                         CX18_ERR("DVB failed to register\n");
 240                         return -EINVAL;
 241                 }
 242         }
 243
 244         if (s->v4l2dev == NULL)
 245                 return 0;
 246
 247         minor = s->v4l2dev->minor;
 248
 249         /* Register device. First try the desired minor, then any free one. */
 250         if (video_register_device(s->v4l2dev, vfl_type, minor) &&
 251                         video_register_device(s->v4l2dev, vfl_type, -1)) {
 252                 CX18_ERR("Couldn't register v4l2 device for %s minor %d\n",
 253                         s->name, minor);
 254                 video_device_release(s->v4l2dev);
 255                 s->v4l2dev = NULL;
 256                 return -ENOMEM;
 257         }
 258         minor = s->v4l2dev->minor;
 259
 260         switch (vfl_type) {
 261         case VFL_TYPE_GRABBER:
 262                 CX18_INFO("Registered device video%d for %s (%d MB)\n",
 263                         minor, s->name, cx->options.megabytes[type]);
 264                 break;
 265
 266         case VFL_TYPE_RADIO:
 267                 CX18_INFO("Registered device radio%d for %s\n",
 268                         minor - MINOR_VFL_TYPE_RADIO_MIN, s->name);
 269                 break;
 270
 271         case VFL_TYPE_VBI:
 272                 if (cx->options.megabytes[type])
 273                         CX18_INFO("Registered device vbi%d for %s (%d MB)\n",
 274                                 minor - MINOR_VFL_TYPE_VBI_MIN,
 275                                 s->name, cx->options.megabytes[type]);
 276                 else
 277                         CX18_INFO("Registered device vbi%d for %s\n",
 278                                 minor - MINOR_VFL_TYPE_VBI_MIN, s->name);
 279                 break;
 280         }
 281
 282         return 0;
 283 }
 284
 285 /* Register v4l2 devices */
 286 int cx18_streams_register(struct cx18 *cx)
 287 {
 288         int type;
 289         int err = 0;
 290
 291         /* Register V4L2 devices */
 292         for (type = 0; type < CX18_MAX_STREAMS; type++)
 293                 err |= cx18_reg_dev(cx, type);
 294
 295         if (err == 0)
 296                 return 0;
 297
 298         /* One or more streams could not be initialized. Clean 'em all up. */
 299         cx18_streams_cleanup(cx, 1);
 300         return -ENOMEM;
 301 }
 302
 303 /* Unregister v4l2 devices */
 304 void cx18_streams_cleanup(struct cx18 *cx, int unregister)
 305 {
 306         struct video_device *vdev;
 307         int type;
 308
 309         /* Teardown all streams */
 310         for (type = 0; type < CX18_MAX_STREAMS; type++) {
 311                 if (cx->streams[type].dvb.enabled) {
 312                         cx18_dvb_unregister(&cx->streams[type]);
 313                         cx->streams[type].dvb.enabled = false;
 314                 }
 315
 316                 vdev = cx->streams[type].v4l2dev;
 317
 318                 cx->streams[type].v4l2dev = NULL;
 319                 if (vdev == NULL)
 320                         continue;
 321
 322                 cx18_stream_free(&cx->streams[type]);
 323
 324                 /* Unregister or release device */
 325                 if (unregister)
 326                         video_unregister_device(vdev);
 327                 else
 328                         video_device_release(vdev);
 329         }
 330 }
 331
 332 static void cx18_vbi_setup(struct cx18_stream *s)
 333 {
 334         struct cx18 *cx = s->cx;
 335         int raw = cx->vbi.sliced_in->service_set == 0;
 336         u32 data[CX2341X_MBOX_MAX_DATA];
 337         int lines;
 338
 339         if (cx->is_60hz) {
 340                 cx->vbi.count = 12;
 341                 cx->vbi.start[0] = 10;
 342                 cx->vbi.start[1] = 273;
 343         } else {        /* PAL/SECAM */
 344                 cx->vbi.count = 18;
 345                 cx->vbi.start[0] = 6;
 346                 cx->vbi.start[1] = 318;
 347         }
 348
 349         /* setup VBI registers */
 350         cx18_av_cmd(cx, VIDIOC_S_FMT, &cx->vbi.in);
 351
 352         /* determine number of lines and total number of VBI bytes.
 353            A raw line takes 1443 bytes: 2 * 720 + 4 byte frame header - 1
 354            The '- 1' byte is probably an unused U or V byte. Or something...
 355            A sliced line takes 51 bytes: 4 byte frame header, 4 byte internal
 356            header, 42 data bytes + checksum (to be confirmed) */
 357         if (raw) {
 358                 lines = cx->vbi.count * 2;
 359         } else {
 360                 lines = cx->is_60hz ? 24 : 38;
 361                 if (cx->is_60hz)
 362                         lines += 2;
 363         }
 364
 365         cx->vbi.enc_size = lines *
 366                 (raw ? cx->vbi.raw_size : cx->vbi.sliced_size);
 367
 368         data[0] = s->handle;
 369         /* Lines per field */
 370         data[1] = (lines / 2) | ((lines / 2) << 16);
 371         /* bytes per line */
 372         data[2] = (raw ? cx->vbi.raw_size : cx->vbi.sliced_size);
 373         /* Every X number of frames a VBI interrupt arrives
 374            (frames as in 25 or 30 fps) */
 375         data[3] = 1;
 376         /* Setup VBI for the cx25840 digitizer */
 377         if (raw) {
 378                 data[4] = 0x20602060;
 379                 data[5] = 0x30703070;
 380         } else {
 381                 data[4] = 0xB0F0B0F0;
 382                 data[5] = 0xA0E0A0E0;
 383         }
 384
 385         CX18_DEBUG_INFO("Setup VBI h: %d lines %x bpl %d fr %d %x %x\n",
 386                         data[0], data[1], data[2], data[3], data[4], data[5]);
 387
 388         if (s->type == CX18_ENC_STREAM_TYPE_VBI)
 389                 cx18_api(cx, CX18_CPU_SET_RAW_VBI_PARAM, 6, data);
 390 }
 391
 392 int cx18_start_v4l2_encode_stream(struct cx18_stream *s)
 393 {
 394         u32 data[MAX_MB_ARGUMENTS];
 395         struct cx18 *cx = s->cx;
 396         struct list_head *p;
 397         int ts = 0;
 398         int captype = 0;
 399
 400         if (s->v4l2dev == NULL && s->dvb.enabled == 0)
 401                 return -EINVAL;
 402
 403         CX18_DEBUG_INFO("Start encoder stream %s\n", s->name);
 404
 405         switch (s->type) {
 406         case CX18_ENC_STREAM_TYPE_MPG:
 407                 captype = CAPTURE_CHANNEL_TYPE_MPEG;
 408                 cx->mpg_data_received = cx->vbi_data_inserted = 0;
 409                 cx->dualwatch_jiffies = jiffies;
 410                 cx->dualwatch_stereo_mode = cx->params.audio_properties & 0x300;
 411                 cx->search_pack_header = 0;
 412                 break;
 413
 414         case CX18_ENC_STREAM_TYPE_TS:
 415                 captype = CAPTURE_CHANNEL_TYPE_TS;
 416                 ts = 1;
 417                 break;
 418         case CX18_ENC_STREAM_TYPE_YUV:
 419                 captype = CAPTURE_CHANNEL_TYPE_YUV;
 420                 break;
 421         case CX18_ENC_STREAM_TYPE_PCM:
 422                 captype = CAPTURE_CHANNEL_TYPE_PCM;
 423                 break;
 424         case CX18_ENC_STREAM_TYPE_VBI:
 425                 captype = cx->vbi.sliced_in->service_set ?
 426                     CAPTURE_CHANNEL_TYPE_SLICED_VBI : CAPTURE_CHANNEL_TYPE_VBI;
 427                 cx->vbi.frame = 0;
 428                 cx->vbi.inserted_frame = 0;
 429                 memset(cx->vbi.sliced_mpeg_size,
 430                         0, sizeof(cx->vbi.sliced_mpeg_size));
 431                 break;
 432         default:
 433                 return -EINVAL;
 434         }
 435         s->buffers_stolen = 0;
 436
 437         /* mute/unmute video */
 438         cx18_vapi(cx, CX18_CPU_SET_VIDEO_MUTE, 2,
 439                   s->handle, !!test_bit(CX18_F_I_RADIO_USER, &cx->i_flags));
 440
 441         /* Clear Streamoff flags in case left from last capture */
 442         clear_bit(CX18_F_S_STREAMOFF, &s->s_flags);
 443
 444         cx18_vapi_result(cx, data, CX18_CREATE_TASK, 1, CPU_CMD_MASK_CAPTURE);
 445         s->handle = data[0];
 446         cx18_vapi(cx, CX18_CPU_SET_CHANNEL_TYPE, 2, s->handle, captype);
 447
 448         if (atomic_read(&cx->ana_capturing) == 0 && !ts) {
 449                 /* Stuff from Windows, we don't know what it is */
 450                 cx18_vapi(cx, CX18_CPU_SET_VER_CROP_LINE, 2, s->handle, 0);
 451                 cx18_vapi(cx, CX18_CPU_SET_MISC_PARAMETERS, 3, s->handle, 3, 1);
 452                 cx18_vapi(cx, CX18_CPU_SET_MISC_PARAMETERS, 3, s->handle, 8, 0);
 453                 cx18_vapi(cx, CX18_CPU_SET_MISC_PARAMETERS, 3, s->handle, 4, 1);
 454                 cx18_vapi(cx, CX18_CPU_SET_MISC_PARAMETERS, 2, s->handle, 12);
 455
 456                 cx18_vapi(cx, CX18_CPU_SET_CAPTURE_LINE_NO, 3,
 457                                s->handle, cx->digitizer, cx->digitizer);
 458
 459                 /* Setup VBI */
 460                 if (cx->v4l2_cap & V4L2_CAP_VBI_CAPTURE)
 461                         cx18_vbi_setup(s);
 462
 463                 /* assign program index info.
 464                    Mask 7: select I/P/B, Num_req: 400 max */
 465                 cx18_vapi_result(cx, data, CX18_CPU_SET_INDEXTABLE, 1, 0);
 466
 467                 /* Setup API for Stream */
 468                 cx2341x_update(cx, cx18_api_func, NULL, &cx->params);
 469         }
 470
 471         if (atomic_read(&cx->tot_capturing) == 0) {
 472                 clear_bit(CX18_F_I_EOS, &cx->i_flags);
 473                 write_reg(7, CX18_DSP0_INTERRUPT_MASK);
 474         }
 475
 476         cx18_vapi(cx, CX18_CPU_DE_SET_MDL_ACK, 3, s->handle,
 477                 (void __iomem *)&cx->scb->cpu_mdl_ack[s->type][0] - cx->enc_mem,
 478                 (void __iomem *)&cx->scb->cpu_mdl_ack[s->type][1] - cx->enc_mem);
 479
 480         list_for_each(p, &s->q_free.list) {
 481                 struct cx18_buffer *buf = list_entry(p, struct cx18_buffer, list);
 482
 483                 writel(buf->dma_handle, &cx->scb->cpu_mdl[buf->id].paddr);
 484                 writel(s->buf_size, &cx->scb->cpu_mdl[buf->id].length);
 485                 cx18_vapi(cx, CX18_CPU_DE_SET_MDL, 5, s->handle,
 486                         (void __iomem *)&cx->scb->cpu_mdl[buf->id] - cx->enc_mem,
 487                         1, buf->id, s->buf_size);
 488         }
 489         /* begin_capture */
 490         if (cx18_vapi(cx, CX18_CPU_CAPTURE_START, 1, s->handle)) {
 491                 CX18_DEBUG_WARN("Error starting capture!\n");
 492                 cx18_vapi(cx, CX18_DESTROY_TASK, 1, s->handle);
 493                 return -EINVAL;
 494         }
 495
 496         /* you're live! sit back and await interrupts :) */
 497         if (!ts)
 498                 atomic_inc(&cx->ana_capturing);
 499         atomic_inc(&cx->tot_capturing);
 500         return 0;
 501 }
 502
 503 void cx18_stop_all_captures(struct cx18 *cx)
 504 {
 505         int i;
 506
 507         for (i = CX18_MAX_STREAMS - 1; i >= 0; i--) {
 508                 struct cx18_stream *s = &cx->streams[i];
 509
 510                 if (s->v4l2dev == NULL && s->dvb.enabled == 0)
 511                         continue;
 512                 if (test_bit(CX18_F_S_STREAMING, &s->s_flags))
 513                         cx18_stop_v4l2_encode_stream(s, 0);
 514         }
 515 }
 516
 517 int cx18_stop_v4l2_encode_stream(struct cx18_stream *s, int gop_end)
 518 {
 519         struct cx18 *cx = s->cx;
 520         unsigned long then;
 521
 522         if (s->v4l2dev == NULL && s->dvb.enabled == 0)
 523                 return -EINVAL;
 524
 525         /* This function assumes that you are allowed to stop the capture
 526            and that we are actually capturing */
 527
 528         CX18_DEBUG_INFO("Stop Capture\n");
 529
 530         if (atomic_read(&cx->tot_capturing) == 0)
 531                 return 0;
 532
 533         if (s->type == CX18_ENC_STREAM_TYPE_MPG)
 534                 cx18_vapi(cx, CX18_CPU_CAPTURE_STOP, 2, s->handle, !gop_end);
 535         else
 536                 cx18_vapi(cx, CX18_CPU_CAPTURE_STOP, 1, s->handle);
 537
 538         then = jiffies;
 539
 540         if (s->type == CX18_ENC_STREAM_TYPE_MPG && gop_end) {
 541                 CX18_INFO("ignoring gop_end: not (yet?) supported by the firmware\n");
 542         }
 543
 544         if (s->type != CX18_ENC_STREAM_TYPE_TS)
 545                 atomic_dec(&cx->ana_capturing);
 546         atomic_dec(&cx->tot_capturing);
 547
 548         /* Clear capture and no-read bits */
 549         clear_bit(CX18_F_S_STREAMING, &s->s_flags);
 550
 551         cx18_vapi(cx, CX18_DESTROY_TASK, 1, s->handle);
 552         s->handle = 0xffffffff;
 553
 554         if (atomic_read(&cx->tot_capturing) > 0)
 555                 return 0;
 556
 557         write_reg(5, CX18_DSP0_INTERRUPT_MASK);
 558         wake_up(&s->waitq);
 559
 560         return 0;
 561 }
 562
 563 u32 cx18_find_handle(struct cx18 *cx)
 564 {
 565         int i;
 566
 567         /* find first available handle to be used for global settings */
 568         for (i = 0; i < CX18_MAX_STREAMS; i++) {
 569                 struct cx18_stream *s = &cx->streams[i];
 570
 571                 if (s->v4l2dev && s->handle)
 572                         return s->handle;
 573         }
 574         return 0;
 575 }