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