root/drivers/media/usb/uvc/uvc_video.c

DEFINITIONS

1. __uvc_query_ctrl
2. uvc_query_name
3. uvc_query_ctrl
4. uvc_fixup_video_ctrl
5. uvc_video_ctrl_size
6. uvc_get_video_ctrl
7. uvc_set_video_ctrl
8. uvc_probe_video
9. uvc_commit_video
10. uvc_video_get_time
11. uvc_video_clock_decode
12. uvc_video_clock_reset
13. uvc_video_clock_init
14. uvc_video_clock_cleanup
15. uvc_video_clock_host_sof
16. uvc_video_clock_update
17. uvc_video_stats_decode
18. uvc_video_stats_update
19. uvc_video_stats_dump
20. uvc_video_stats_start
21. uvc_video_stats_stop
22. uvc_video_decode_start
23. uvc_video_copy_data_work
24. uvc_video_decode_data
25. uvc_video_decode_end
26. uvc_video_encode_header
27. uvc_video_encode_data
28. uvc_video_decode_meta
29. uvc_video_validate_buffer
30. uvc_video_next_buffers
31. uvc_video_decode_isoc
32. uvc_video_decode_bulk
33. uvc_video_encode_bulk
34. uvc_video_complete
35. uvc_free_urb_buffers
36. uvc_alloc_urb_buffers
37. uvc_video_stop_transfer
38. uvc_endpoint_max_bpi
39. uvc_init_video_isoc
40. uvc_init_video_bulk
41. uvc_video_start_transfer
42. uvc_video_suspend
43. uvc_video_resume
44. uvc_video_init
45. uvc_video_start_streaming
46. uvc_video_stop_streaming

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      uvc_video.c  --  USB Video Class driver - Video handling
   4  *
   5  *      Copyright (C) 2005-2010
   6  *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/list.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/usb.h>
  14 #include <linux/videodev2.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/wait.h>
  17 #include <linux/atomic.h>
  18 #include <asm/unaligned.h>
  19 
  20 #include <media/v4l2-common.h>
  21 
  22 #include "uvcvideo.h"
  23 
  24 /* ------------------------------------------------------------------------
  25  * UVC Controls
  26  */
  27 
  28 static int __uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
  29                         u8 intfnum, u8 cs, void *data, u16 size,
  30                         int timeout)
  31 {
  32         u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
  33         unsigned int pipe;
  34 
  35         pipe = (query & 0x80) ? usb_rcvctrlpipe(dev->udev, 0)
  36                               : usb_sndctrlpipe(dev->udev, 0);
  37         type |= (query & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
  38 
  39         return usb_control_msg(dev->udev, pipe, query, type, cs << 8,
  40                         unit << 8 | intfnum, data, size, timeout);
  41 }
  42 
  43 static const char *uvc_query_name(u8 query)
  44 {
  45         switch (query) {
  46         case UVC_SET_CUR:
  47                 return "SET_CUR";
  48         case UVC_GET_CUR:
  49                 return "GET_CUR";
  50         case UVC_GET_MIN:
  51                 return "GET_MIN";
  52         case UVC_GET_MAX:
  53                 return "GET_MAX";
  54         case UVC_GET_RES:
  55                 return "GET_RES";
  56         case UVC_GET_LEN:
  57                 return "GET_LEN";
  58         case UVC_GET_INFO:
  59                 return "GET_INFO";
  60         case UVC_GET_DEF:
  61                 return "GET_DEF";
  62         default:
  63                 return "<invalid>";
  64         }
  65 }
  66 
  67 int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
  68                         u8 intfnum, u8 cs, void *data, u16 size)
  69 {
  70         int ret;
  71         u8 error;
  72         u8 tmp;
  73 
  74         ret = __uvc_query_ctrl(dev, query, unit, intfnum, cs, data, size,
  75                                 UVC_CTRL_CONTROL_TIMEOUT);
  76         if (likely(ret == size))
  77                 return 0;
  78 
  79         uvc_printk(KERN_ERR,
  80                    "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
  81                    uvc_query_name(query), cs, unit, ret, size);
  82 
  83         if (ret != -EPIPE)
  84                 return ret;
  85 
  86         tmp = *(u8 *)data;
  87 
  88         ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum,
  89                                UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1,
  90                                UVC_CTRL_CONTROL_TIMEOUT);
  91 
  92         error = *(u8 *)data;
  93         *(u8 *)data = tmp;
  94 
  95         if (ret != 1)
  96                 return ret < 0 ? ret : -EPIPE;
  97 
  98         uvc_trace(UVC_TRACE_CONTROL, "Control error %u\n", error);
  99 
 100         switch (error) {
 101         case 0:
 102                 /* Cannot happen - we received a STALL */
 103                 return -EPIPE;
 104         case 1: /* Not ready */
 105                 return -EBUSY;
 106         case 2: /* Wrong state */
 107                 return -EILSEQ;
 108         case 3: /* Power */
 109                 return -EREMOTE;
 110         case 4: /* Out of range */
 111                 return -ERANGE;
 112         case 5: /* Invalid unit */
 113         case 6: /* Invalid control */
 114         case 7: /* Invalid Request */
 115         case 8: /* Invalid value within range */
 116                 return -EINVAL;
 117         default: /* reserved or unknown */
 118                 break;
 119         }
 120 
 121         return -EPIPE;
 122 }
 123 
 124 static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
 125         struct uvc_streaming_control *ctrl)
 126 {
 127         struct uvc_format *format = NULL;
 128         struct uvc_frame *frame = NULL;
 129         unsigned int i;
 130 
 131         for (i = 0; i < stream->nformats; ++i) {
 132                 if (stream->format[i].index == ctrl->bFormatIndex) {
 133                         format = &stream->format[i];
 134                         break;
 135                 }
 136         }
 137 
 138         if (format == NULL)
 139                 return;
 140 
 141         for (i = 0; i < format->nframes; ++i) {
 142                 if (format->frame[i].bFrameIndex == ctrl->bFrameIndex) {
 143                         frame = &format->frame[i];
 144                         break;
 145                 }
 146         }
 147 
 148         if (frame == NULL)
 149                 return;
 150 
 151         if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
 152              (ctrl->dwMaxVideoFrameSize == 0 &&
 153               stream->dev->uvc_version < 0x0110))
 154                 ctrl->dwMaxVideoFrameSize =
 155                         frame->dwMaxVideoFrameBufferSize;
 156 
 157         /* The "TOSHIBA Web Camera - 5M" Chicony device (04f2:b50b) seems to
 158          * compute the bandwidth on 16 bits and erroneously sign-extend it to
 159          * 32 bits, resulting in a huge bandwidth value. Detect and fix that
 160          * condition by setting the 16 MSBs to 0 when they're all equal to 1.
 161          */
 162         if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
 163                 ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
 164 
 165         if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
 166             stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
 167             stream->intf->num_altsetting > 1) {
 168                 u32 interval;
 169                 u32 bandwidth;
 170 
 171                 interval = (ctrl->dwFrameInterval > 100000)
 172                          ? ctrl->dwFrameInterval
 173                          : frame->dwFrameInterval[0];
 174 
 175                 /* Compute a bandwidth estimation by multiplying the frame
 176                  * size by the number of video frames per second, divide the
 177                  * result by the number of USB frames (or micro-frames for
 178                  * high-speed devices) per second and add the UVC header size
 179                  * (assumed to be 12 bytes long).
 180                  */
 181                 bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp;
 182                 bandwidth *= 10000000 / interval + 1;
 183                 bandwidth /= 1000;
 184                 if (stream->dev->udev->speed == USB_SPEED_HIGH)
 185                         bandwidth /= 8;
 186                 bandwidth += 12;
 187 
 188                 /* The bandwidth estimate is too low for many cameras. Don't use
 189                  * maximum packet sizes lower than 1024 bytes to try and work
 190                  * around the problem. According to measurements done on two
 191                  * different camera models, the value is high enough to get most
 192                  * resolutions working while not preventing two simultaneous
 193                  * VGA streams at 15 fps.
 194                  */
 195                 bandwidth = max_t(u32, bandwidth, 1024);
 196 
 197                 ctrl->dwMaxPayloadTransferSize = bandwidth;
 198         }
 199 }
 200 
 201 static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
 202 {
 203         /*
 204          * Return the size of the video probe and commit controls, which depends
 205          * on the protocol version.
 206          */
 207         if (stream->dev->uvc_version < 0x0110)
 208                 return 26;
 209         else if (stream->dev->uvc_version < 0x0150)
 210                 return 34;
 211         else
 212                 return 48;
 213 }
 214 
 215 static int uvc_get_video_ctrl(struct uvc_streaming *stream,
 216         struct uvc_streaming_control *ctrl, int probe, u8 query)
 217 {
 218         u16 size = uvc_video_ctrl_size(stream);
 219         u8 *data;
 220         int ret;
 221 
 222         if ((stream->dev->quirks & UVC_QUIRK_PROBE_DEF) &&
 223                         query == UVC_GET_DEF)
 224                 return -EIO;
 225 
 226         data = kmalloc(size, GFP_KERNEL);
 227         if (data == NULL)
 228                 return -ENOMEM;
 229 
 230         ret = __uvc_query_ctrl(stream->dev, query, 0, stream->intfnum,
 231                 probe ? UVC_VS_PROBE_CONTROL : UVC_VS_COMMIT_CONTROL, data,
 232                 size, uvc_timeout_param);
 233 
 234         if ((query == UVC_GET_MIN || query == UVC_GET_MAX) && ret == 2) {
 235                 /* Some cameras, mostly based on Bison Electronics chipsets,
 236                  * answer a GET_MIN or GET_MAX request with the wCompQuality
 237                  * field only.
 238                  */
 239                 uvc_warn_once(stream->dev, UVC_WARN_MINMAX, "UVC non "
 240                         "compliance - GET_MIN/MAX(PROBE) incorrectly "
 241                         "supported. Enabling workaround.\n");
 242                 memset(ctrl, 0, sizeof(*ctrl));
 243                 ctrl->wCompQuality = le16_to_cpup((__le16 *)data);
 244                 ret = 0;
 245                 goto out;
 246         } else if (query == UVC_GET_DEF && probe == 1 && ret != size) {
 247                 /* Many cameras don't support the GET_DEF request on their
 248                  * video probe control. Warn once and return, the caller will
 249                  * fall back to GET_CUR.
 250                  */
 251                 uvc_warn_once(stream->dev, UVC_WARN_PROBE_DEF, "UVC non "
 252                         "compliance - GET_DEF(PROBE) not supported. "
 253                         "Enabling workaround.\n");
 254                 ret = -EIO;
 255                 goto out;
 256         } else if (ret != size) {
 257                 uvc_printk(KERN_ERR, "Failed to query (%u) UVC %s control : "
 258                         "%d (exp. %u).\n", query, probe ? "probe" : "commit",
 259                         ret, size);
 260                 ret = -EIO;
 261                 goto out;
 262         }
 263 
 264         ctrl->bmHint = le16_to_cpup((__le16 *)&data[0]);
 265         ctrl->bFormatIndex = data[2];
 266         ctrl->bFrameIndex = data[3];
 267         ctrl->dwFrameInterval = le32_to_cpup((__le32 *)&data[4]);
 268         ctrl->wKeyFrameRate = le16_to_cpup((__le16 *)&data[8]);
 269         ctrl->wPFrameRate = le16_to_cpup((__le16 *)&data[10]);
 270         ctrl->wCompQuality = le16_to_cpup((__le16 *)&data[12]);
 271         ctrl->wCompWindowSize = le16_to_cpup((__le16 *)&data[14]);
 272         ctrl->wDelay = le16_to_cpup((__le16 *)&data[16]);
 273         ctrl->dwMaxVideoFrameSize = get_unaligned_le32(&data[18]);
 274         ctrl->dwMaxPayloadTransferSize = get_unaligned_le32(&data[22]);
 275 
 276         if (size >= 34) {
 277                 ctrl->dwClockFrequency = get_unaligned_le32(&data[26]);
 278                 ctrl->bmFramingInfo = data[30];
 279                 ctrl->bPreferedVersion = data[31];
 280                 ctrl->bMinVersion = data[32];
 281                 ctrl->bMaxVersion = data[33];
 282         } else {
 283                 ctrl->dwClockFrequency = stream->dev->clock_frequency;
 284                 ctrl->bmFramingInfo = 0;
 285                 ctrl->bPreferedVersion = 0;
 286                 ctrl->bMinVersion = 0;
 287                 ctrl->bMaxVersion = 0;
 288         }
 289 
 290         /* Some broken devices return null or wrong dwMaxVideoFrameSize and
 291          * dwMaxPayloadTransferSize fields. Try to get the value from the
 292          * format and frame descriptors.
 293          */
 294         uvc_fixup_video_ctrl(stream, ctrl);
 295         ret = 0;
 296 
 297 out:
 298         kfree(data);
 299         return ret;
 300 }
 301 
 302 static int uvc_set_video_ctrl(struct uvc_streaming *stream,
 303         struct uvc_streaming_control *ctrl, int probe)
 304 {
 305         u16 size = uvc_video_ctrl_size(stream);
 306         u8 *data;
 307         int ret;
 308 
 309         data = kzalloc(size, GFP_KERNEL);
 310         if (data == NULL)
 311                 return -ENOMEM;
 312 
 313         *(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
 314         data[2] = ctrl->bFormatIndex;
 315         data[3] = ctrl->bFrameIndex;
 316         *(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
 317         *(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
 318         *(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
 319         *(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
 320         *(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
 321         *(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
 322         put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
 323         put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
 324 
 325         if (size >= 34) {
 326                 put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
 327                 data[30] = ctrl->bmFramingInfo;
 328                 data[31] = ctrl->bPreferedVersion;
 329                 data[32] = ctrl->bMinVersion;
 330                 data[33] = ctrl->bMaxVersion;
 331         }
 332 
 333         ret = __uvc_query_ctrl(stream->dev, UVC_SET_CUR, 0, stream->intfnum,
 334                 probe ? UVC_VS_PROBE_CONTROL : UVC_VS_COMMIT_CONTROL, data,
 335                 size, uvc_timeout_param);
 336         if (ret != size) {
 337                 uvc_printk(KERN_ERR, "Failed to set UVC %s control : "
 338                         "%d (exp. %u).\n", probe ? "probe" : "commit",
 339                         ret, size);
 340                 ret = -EIO;
 341         }
 342 
 343         kfree(data);
 344         return ret;
 345 }
 346 
 347 int uvc_probe_video(struct uvc_streaming *stream,
 348         struct uvc_streaming_control *probe)
 349 {
 350         struct uvc_streaming_control probe_min, probe_max;
 351         u16 bandwidth;
 352         unsigned int i;
 353         int ret;
 354 
 355         /* Perform probing. The device should adjust the requested values
 356          * according to its capabilities. However, some devices, namely the
 357          * first generation UVC Logitech webcams, don't implement the Video
 358          * Probe control properly, and just return the needed bandwidth. For
 359          * that reason, if the needed bandwidth exceeds the maximum available
 360          * bandwidth, try to lower the quality.
 361          */
 362         ret = uvc_set_video_ctrl(stream, probe, 1);
 363         if (ret < 0)
 364                 goto done;
 365 
 366         /* Get the minimum and maximum values for compression settings. */
 367         if (!(stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX)) {
 368                 ret = uvc_get_video_ctrl(stream, &probe_min, 1, UVC_GET_MIN);
 369                 if (ret < 0)
 370                         goto done;
 371                 ret = uvc_get_video_ctrl(stream, &probe_max, 1, UVC_GET_MAX);
 372                 if (ret < 0)
 373                         goto done;
 374 
 375                 probe->wCompQuality = probe_max.wCompQuality;
 376         }
 377 
 378         for (i = 0; i < 2; ++i) {
 379                 ret = uvc_set_video_ctrl(stream, probe, 1);
 380                 if (ret < 0)
 381                         goto done;
 382                 ret = uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);
 383                 if (ret < 0)
 384                         goto done;
 385 
 386                 if (stream->intf->num_altsetting == 1)
 387                         break;
 388 
 389                 bandwidth = probe->dwMaxPayloadTransferSize;
 390                 if (bandwidth <= stream->maxpsize)
 391                         break;
 392 
 393                 if (stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX) {
 394                         ret = -ENOSPC;
 395                         goto done;
 396                 }
 397 
 398                 /* TODO: negotiate compression parameters */
 399                 probe->wKeyFrameRate = probe_min.wKeyFrameRate;
 400                 probe->wPFrameRate = probe_min.wPFrameRate;
 401                 probe->wCompQuality = probe_max.wCompQuality;
 402                 probe->wCompWindowSize = probe_min.wCompWindowSize;
 403         }
 404 
 405 done:
 406         return ret;
 407 }
 408 
 409 static int uvc_commit_video(struct uvc_streaming *stream,
 410                             struct uvc_streaming_control *probe)
 411 {
 412         return uvc_set_video_ctrl(stream, probe, 0);
 413 }
 414 
 415 /* -----------------------------------------------------------------------------
 416  * Clocks and timestamps
 417  */
 418 
 419 static inline ktime_t uvc_video_get_time(void)
 420 {
 421         if (uvc_clock_param == CLOCK_MONOTONIC)
 422                 return ktime_get();
 423         else
 424                 return ktime_get_real();
 425 }
 426 
 427 static void
 428 uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 429                        const u8 *data, int len)
 430 {
 431         struct uvc_clock_sample *sample;
 432         unsigned int header_size;
 433         bool has_pts = false;
 434         bool has_scr = false;
 435         unsigned long flags;
 436         ktime_t time;
 437         u16 host_sof;
 438         u16 dev_sof;
 439 
 440         switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 441         case UVC_STREAM_PTS | UVC_STREAM_SCR:
 442                 header_size = 12;
 443                 has_pts = true;
 444                 has_scr = true;
 445                 break;
 446         case UVC_STREAM_PTS:
 447                 header_size = 6;
 448                 has_pts = true;
 449                 break;
 450         case UVC_STREAM_SCR:
 451                 header_size = 8;
 452                 has_scr = true;
 453                 break;
 454         default:
 455                 header_size = 2;
 456                 break;
 457         }
 458 
 459         /* Check for invalid headers. */
 460         if (len < header_size)
 461                 return;
 462 
 463         /* Extract the timestamps:
 464          *
 465          * - store the frame PTS in the buffer structure
 466          * - if the SCR field is present, retrieve the host SOF counter and
 467          *   kernel timestamps and store them with the SCR STC and SOF fields
 468          *   in the ring buffer
 469          */
 470         if (has_pts && buf != NULL)
 471                 buf->pts = get_unaligned_le32(&data[2]);
 472 
 473         if (!has_scr)
 474                 return;
 475 
 476         /* To limit the amount of data, drop SCRs with an SOF identical to the
 477          * previous one.
 478          */
 479         dev_sof = get_unaligned_le16(&data[header_size - 2]);
 480         if (dev_sof == stream->clock.last_sof)
 481                 return;
 482 
 483         stream->clock.last_sof = dev_sof;
 484 
 485         host_sof = usb_get_current_frame_number(stream->dev->udev);
 486         time = uvc_video_get_time();
 487 
 488         /* The UVC specification allows device implementations that can't obtain
 489          * the USB frame number to keep their own frame counters as long as they
 490          * match the size and frequency of the frame number associated with USB
 491          * SOF tokens. The SOF values sent by such devices differ from the USB
 492          * SOF tokens by a fixed offset that needs to be estimated and accounted
 493          * for to make timestamp recovery as accurate as possible.
 494          *
 495          * The offset is estimated the first time a device SOF value is received
 496          * as the difference between the host and device SOF values. As the two
 497          * SOF values can differ slightly due to transmission delays, consider
 498          * that the offset is null if the difference is not higher than 10 ms
 499          * (negative differences can not happen and are thus considered as an
 500          * offset). The video commit control wDelay field should be used to
 501          * compute a dynamic threshold instead of using a fixed 10 ms value, but
 502          * devices don't report reliable wDelay values.
 503          *
 504          * See uvc_video_clock_host_sof() for an explanation regarding why only
 505          * the 8 LSBs of the delta are kept.
 506          */
 507         if (stream->clock.sof_offset == (u16)-1) {
 508                 u16 delta_sof = (host_sof - dev_sof) & 255;
 509                 if (delta_sof >= 10)
 510                         stream->clock.sof_offset = delta_sof;
 511                 else
 512                         stream->clock.sof_offset = 0;
 513         }
 514 
 515         dev_sof = (dev_sof + stream->clock.sof_offset) & 2047;
 516 
 517         spin_lock_irqsave(&stream->clock.lock, flags);
 518 
 519         sample = &stream->clock.samples[stream->clock.head];
 520         sample->dev_stc = get_unaligned_le32(&data[header_size - 6]);
 521         sample->dev_sof = dev_sof;
 522         sample->host_sof = host_sof;
 523         sample->host_time = time;
 524 
 525         /* Update the sliding window head and count. */
 526         stream->clock.head = (stream->clock.head + 1) % stream->clock.size;
 527 
 528         if (stream->clock.count < stream->clock.size)
 529                 stream->clock.count++;
 530 
 531         spin_unlock_irqrestore(&stream->clock.lock, flags);
 532 }
 533 
 534 static void uvc_video_clock_reset(struct uvc_streaming *stream)
 535 {
 536         struct uvc_clock *clock = &stream->clock;
 537 
 538         clock->head = 0;
 539         clock->count = 0;
 540         clock->last_sof = -1;
 541         clock->sof_offset = -1;
 542 }
 543 
 544 static int uvc_video_clock_init(struct uvc_streaming *stream)
 545 {
 546         struct uvc_clock *clock = &stream->clock;
 547 
 548         spin_lock_init(&clock->lock);
 549         clock->size = 32;
 550 
 551         clock->samples = kmalloc_array(clock->size, sizeof(*clock->samples),
 552                                        GFP_KERNEL);
 553         if (clock->samples == NULL)
 554                 return -ENOMEM;
 555 
 556         uvc_video_clock_reset(stream);
 557 
 558         return 0;
 559 }
 560 
 561 static void uvc_video_clock_cleanup(struct uvc_streaming *stream)
 562 {
 563         kfree(stream->clock.samples);
 564         stream->clock.samples = NULL;
 565 }
 566 
 567 /*
 568  * uvc_video_clock_host_sof - Return the host SOF value for a clock sample
 569  *
 570  * Host SOF counters reported by usb_get_current_frame_number() usually don't
 571  * cover the whole 11-bits SOF range (0-2047) but are limited to the HCI frame
 572  * schedule window. They can be limited to 8, 9 or 10 bits depending on the host
 573  * controller and its configuration.
 574  *
 575  * We thus need to recover the SOF value corresponding to the host frame number.
 576  * As the device and host frame numbers are sampled in a short interval, the
 577  * difference between their values should be equal to a small delta plus an
 578  * integer multiple of 256 caused by the host frame number limited precision.
 579  *
 580  * To obtain the recovered host SOF value, compute the small delta by masking
 581  * the high bits of the host frame counter and device SOF difference and add it
 582  * to the device SOF value.
 583  */
 584 static u16 uvc_video_clock_host_sof(const struct uvc_clock_sample *sample)
 585 {
 586         /* The delta value can be negative. */
 587         s8 delta_sof;
 588 
 589         delta_sof = (sample->host_sof - sample->dev_sof) & 255;
 590 
 591         return (sample->dev_sof + delta_sof) & 2047;
 592 }
 593 
 594 /*
 595  * uvc_video_clock_update - Update the buffer timestamp
 596  *
 597  * This function converts the buffer PTS timestamp to the host clock domain by
 598  * going through the USB SOF clock domain and stores the result in the V4L2
 599  * buffer timestamp field.
 600  *
 601  * The relationship between the device clock and the host clock isn't known.
 602  * However, the device and the host share the common USB SOF clock which can be
 603  * used to recover that relationship.
 604  *
 605  * The relationship between the device clock and the USB SOF clock is considered
 606  * to be linear over the clock samples sliding window and is given by
 607  *
 608  * SOF = m * PTS + p
 609  *
 610  * Several methods to compute the slope (m) and intercept (p) can be used. As
 611  * the clock drift should be small compared to the sliding window size, we
 612  * assume that the line that goes through the points at both ends of the window
 613  * is a good approximation. Naming those points P1 and P2, we get
 614  *
 615  * SOF = (SOF2 - SOF1) / (STC2 - STC1) * PTS
 616  *     + (SOF1 * STC2 - SOF2 * STC1) / (STC2 - STC1)
 617  *
 618  * or
 619  *
 620  * SOF = ((SOF2 - SOF1) * PTS + SOF1 * STC2 - SOF2 * STC1) / (STC2 - STC1)   (1)
 621  *
 622  * to avoid losing precision in the division. Similarly, the host timestamp is
 623  * computed with
 624  *
 625  * TS = ((TS2 - TS1) * PTS + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1)        (2)
 626  *
 627  * SOF values are coded on 11 bits by USB. We extend their precision with 16
 628  * decimal bits, leading to a 11.16 coding.
 629  *
 630  * TODO: To avoid surprises with device clock values, PTS/STC timestamps should
 631  * be normalized using the nominal device clock frequency reported through the
 632  * UVC descriptors.
 633  *
 634  * Both the PTS/STC and SOF counters roll over, after a fixed but device
 635  * specific amount of time for PTS/STC and after 2048ms for SOF. As long as the
 636  * sliding window size is smaller than the rollover period, differences computed
 637  * on unsigned integers will produce the correct result. However, the p term in
 638  * the linear relations will be miscomputed.
 639  *
 640  * To fix the issue, we subtract a constant from the PTS and STC values to bring
 641  * PTS to half the 32 bit STC range. The sliding window STC values then fit into
 642  * the 32 bit range without any rollover.
 643  *
 644  * Similarly, we add 2048 to the device SOF values to make sure that the SOF
 645  * computed by (1) will never be smaller than 0. This offset is then compensated
 646  * by adding 2048 to the SOF values used in (2). However, this doesn't prevent
 647  * rollovers between (1) and (2): the SOF value computed by (1) can be slightly
 648  * lower than 4096, and the host SOF counters can have rolled over to 2048. This
 649  * case is handled by subtracting 2048 from the SOF value if it exceeds the host
 650  * SOF value at the end of the sliding window.
 651  *
 652  * Finally we subtract a constant from the host timestamps to bring the first
 653  * timestamp of the sliding window to 1s.
 654  */
 655 void uvc_video_clock_update(struct uvc_streaming *stream,
 656                             struct vb2_v4l2_buffer *vbuf,
 657                             struct uvc_buffer *buf)
 658 {
 659         struct uvc_clock *clock = &stream->clock;
 660         struct uvc_clock_sample *first;
 661         struct uvc_clock_sample *last;
 662         unsigned long flags;
 663         u64 timestamp;
 664         u32 delta_stc;
 665         u32 y1, y2;
 666         u32 x1, x2;
 667         u32 mean;
 668         u32 sof;
 669         u64 y;
 670 
 671         if (!uvc_hw_timestamps_param)
 672                 return;
 673 
 674         /*
 675          * We will get called from __vb2_queue_cancel() if there are buffers
 676          * done but not dequeued by the user, but the sample array has already
 677          * been released at that time. Just bail out in that case.
 678          */
 679         if (!clock->samples)
 680                 return;
 681 
 682         spin_lock_irqsave(&clock->lock, flags);
 683 
 684         if (clock->count < clock->size)
 685                 goto done;
 686 
 687         first = &clock->samples[clock->head];
 688         last = &clock->samples[(clock->head - 1) % clock->size];
 689 
 690         /* First step, PTS to SOF conversion. */
 691         delta_stc = buf->pts - (1UL << 31);
 692         x1 = first->dev_stc - delta_stc;
 693         x2 = last->dev_stc - delta_stc;
 694         if (x1 == x2)
 695                 goto done;
 696 
 697         y1 = (first->dev_sof + 2048) << 16;
 698         y2 = (last->dev_sof + 2048) << 16;
 699         if (y2 < y1)
 700                 y2 += 2048 << 16;
 701 
 702         y = (u64)(y2 - y1) * (1ULL << 31) + (u64)y1 * (u64)x2
 703           - (u64)y2 * (u64)x1;
 704         y = div_u64(y, x2 - x1);
 705 
 706         sof = y;
 707 
 708         uvc_trace(UVC_TRACE_CLOCK, "%s: PTS %u y %llu.%06llu SOF %u.%06llu "
 709                   "(x1 %u x2 %u y1 %u y2 %u SOF offset %u)\n",
 710                   stream->dev->name, buf->pts,
 711                   y >> 16, div_u64((y & 0xffff) * 1000000, 65536),
 712                   sof >> 16, div_u64(((u64)sof & 0xffff) * 1000000LLU, 65536),
 713                   x1, x2, y1, y2, clock->sof_offset);
 714 
 715         /* Second step, SOF to host clock conversion. */
 716         x1 = (uvc_video_clock_host_sof(first) + 2048) << 16;
 717         x2 = (uvc_video_clock_host_sof(last) + 2048) << 16;
 718         if (x2 < x1)
 719                 x2 += 2048 << 16;
 720         if (x1 == x2)
 721                 goto done;
 722 
 723         y1 = NSEC_PER_SEC;
 724         y2 = (u32)ktime_to_ns(ktime_sub(last->host_time, first->host_time)) + y1;
 725 
 726         /* Interpolated and host SOF timestamps can wrap around at slightly
 727          * different times. Handle this by adding or removing 2048 to or from
 728          * the computed SOF value to keep it close to the SOF samples mean
 729          * value.
 730          */
 731         mean = (x1 + x2) / 2;
 732         if (mean - (1024 << 16) > sof)
 733                 sof += 2048 << 16;
 734         else if (sof > mean + (1024 << 16))
 735                 sof -= 2048 << 16;
 736 
 737         y = (u64)(y2 - y1) * (u64)sof + (u64)y1 * (u64)x2
 738           - (u64)y2 * (u64)x1;
 739         y = div_u64(y, x2 - x1);
 740 
 741         timestamp = ktime_to_ns(first->host_time) + y - y1;
 742 
 743         uvc_trace(UVC_TRACE_CLOCK, "%s: SOF %u.%06llu y %llu ts %llu "
 744                   "buf ts %llu (x1 %u/%u/%u x2 %u/%u/%u y1 %u y2 %u)\n",
 745                   stream->dev->name,
 746                   sof >> 16, div_u64(((u64)sof & 0xffff) * 1000000LLU, 65536),
 747                   y, timestamp, vbuf->vb2_buf.timestamp,
 748                   x1, first->host_sof, first->dev_sof,
 749                   x2, last->host_sof, last->dev_sof, y1, y2);
 750 
 751         /* Update the V4L2 buffer. */
 752         vbuf->vb2_buf.timestamp = timestamp;
 753 
 754 done:
 755         spin_unlock_irqrestore(&clock->lock, flags);
 756 }
 757 
 758 /* ------------------------------------------------------------------------
 759  * Stream statistics
 760  */
 761 
 762 static void uvc_video_stats_decode(struct uvc_streaming *stream,
 763                 const u8 *data, int len)
 764 {
 765         unsigned int header_size;
 766         bool has_pts = false;
 767         bool has_scr = false;
 768         u16 uninitialized_var(scr_sof);
 769         u32 uninitialized_var(scr_stc);
 770         u32 uninitialized_var(pts);
 771 
 772         if (stream->stats.stream.nb_frames == 0 &&
 773             stream->stats.frame.nb_packets == 0)
 774                 stream->stats.stream.start_ts = ktime_get();
 775 
 776         switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 777         case UVC_STREAM_PTS | UVC_STREAM_SCR:
 778                 header_size = 12;
 779                 has_pts = true;
 780                 has_scr = true;
 781                 break;
 782         case UVC_STREAM_PTS:
 783                 header_size = 6;
 784                 has_pts = true;
 785                 break;
 786         case UVC_STREAM_SCR:
 787                 header_size = 8;
 788                 has_scr = true;
 789                 break;
 790         default:
 791                 header_size = 2;
 792                 break;
 793         }
 794 
 795         /* Check for invalid headers. */
 796         if (len < header_size || data[0] < header_size) {
 797                 stream->stats.frame.nb_invalid++;
 798                 return;
 799         }
 800 
 801         /* Extract the timestamps. */
 802         if (has_pts)
 803                 pts = get_unaligned_le32(&data[2]);
 804 
 805         if (has_scr) {
 806                 scr_stc = get_unaligned_le32(&data[header_size - 6]);
 807                 scr_sof = get_unaligned_le16(&data[header_size - 2]);
 808         }
 809 
 810         /* Is PTS constant through the whole frame ? */
 811         if (has_pts && stream->stats.frame.nb_pts) {
 812                 if (stream->stats.frame.pts != pts) {
 813                         stream->stats.frame.nb_pts_diffs++;
 814                         stream->stats.frame.last_pts_diff =
 815                                 stream->stats.frame.nb_packets;
 816                 }
 817         }
 818 
 819         if (has_pts) {
 820                 stream->stats.frame.nb_pts++;
 821                 stream->stats.frame.pts = pts;
 822         }
 823 
 824         /* Do all frames have a PTS in their first non-empty packet, or before
 825          * their first empty packet ?
 826          */
 827         if (stream->stats.frame.size == 0) {
 828                 if (len > header_size)
 829                         stream->stats.frame.has_initial_pts = has_pts;
 830                 if (len == header_size && has_pts)
 831                         stream->stats.frame.has_early_pts = true;
 832         }
 833 
 834         /* Do the SCR.STC and SCR.SOF fields vary through the frame ? */
 835         if (has_scr && stream->stats.frame.nb_scr) {
 836                 if (stream->stats.frame.scr_stc != scr_stc)
 837                         stream->stats.frame.nb_scr_diffs++;
 838         }
 839 
 840         if (has_scr) {
 841                 /* Expand the SOF counter to 32 bits and store its value. */
 842                 if (stream->stats.stream.nb_frames > 0 ||
 843                     stream->stats.frame.nb_scr > 0)
 844                         stream->stats.stream.scr_sof_count +=
 845                                 (scr_sof - stream->stats.stream.scr_sof) % 2048;
 846                 stream->stats.stream.scr_sof = scr_sof;
 847 
 848                 stream->stats.frame.nb_scr++;
 849                 stream->stats.frame.scr_stc = scr_stc;
 850                 stream->stats.frame.scr_sof = scr_sof;
 851 
 852                 if (scr_sof < stream->stats.stream.min_sof)
 853                         stream->stats.stream.min_sof = scr_sof;
 854                 if (scr_sof > stream->stats.stream.max_sof)
 855                         stream->stats.stream.max_sof = scr_sof;
 856         }
 857 
 858         /* Record the first non-empty packet number. */
 859         if (stream->stats.frame.size == 0 && len > header_size)
 860                 stream->stats.frame.first_data = stream->stats.frame.nb_packets;
 861 
 862         /* Update the frame size. */
 863         stream->stats.frame.size += len - header_size;
 864 
 865         /* Update the packets counters. */
 866         stream->stats.frame.nb_packets++;
 867         if (len <= header_size)
 868                 stream->stats.frame.nb_empty++;
 869 
 870         if (data[1] & UVC_STREAM_ERR)
 871                 stream->stats.frame.nb_errors++;
 872 }
 873 
 874 static void uvc_video_stats_update(struct uvc_streaming *stream)
 875 {
 876         struct uvc_stats_frame *frame = &stream->stats.frame;
 877 
 878         uvc_trace(UVC_TRACE_STATS, "frame %u stats: %u/%u/%u packets, "
 879                   "%u/%u/%u pts (%searly %sinitial), %u/%u scr, "
 880                   "last pts/stc/sof %u/%u/%u\n",
 881                   stream->sequence, frame->first_data,
 882                   frame->nb_packets - frame->nb_empty, frame->nb_packets,
 883                   frame->nb_pts_diffs, frame->last_pts_diff, frame->nb_pts,
 884                   frame->has_early_pts ? "" : "!",
 885                   frame->has_initial_pts ? "" : "!",
 886                   frame->nb_scr_diffs, frame->nb_scr,
 887                   frame->pts, frame->scr_stc, frame->scr_sof);
 888 
 889         stream->stats.stream.nb_frames++;
 890         stream->stats.stream.nb_packets += stream->stats.frame.nb_packets;
 891         stream->stats.stream.nb_empty += stream->stats.frame.nb_empty;
 892         stream->stats.stream.nb_errors += stream->stats.frame.nb_errors;
 893         stream->stats.stream.nb_invalid += stream->stats.frame.nb_invalid;
 894 
 895         if (frame->has_early_pts)
 896                 stream->stats.stream.nb_pts_early++;
 897         if (frame->has_initial_pts)
 898                 stream->stats.stream.nb_pts_initial++;
 899         if (frame->last_pts_diff <= frame->first_data)
 900                 stream->stats.stream.nb_pts_constant++;
 901         if (frame->nb_scr >= frame->nb_packets - frame->nb_empty)
 902                 stream->stats.stream.nb_scr_count_ok++;
 903         if (frame->nb_scr_diffs + 1 == frame->nb_scr)
 904                 stream->stats.stream.nb_scr_diffs_ok++;
 905 
 906         memset(&stream->stats.frame, 0, sizeof(stream->stats.frame));
 907 }
 908 
 909 size_t uvc_video_stats_dump(struct uvc_streaming *stream, char *buf,
 910                             size_t size)
 911 {
 912         unsigned int scr_sof_freq;
 913         unsigned int duration;
 914         size_t count = 0;
 915 
 916         /* Compute the SCR.SOF frequency estimate. At the nominal 1kHz SOF
 917          * frequency this will not overflow before more than 1h.
 918          */
 919         duration = ktime_ms_delta(stream->stats.stream.stop_ts,
 920                                   stream->stats.stream.start_ts);
 921         if (duration != 0)
 922                 scr_sof_freq = stream->stats.stream.scr_sof_count * 1000
 923                              / duration;
 924         else
 925                 scr_sof_freq = 0;
 926 
 927         count += scnprintf(buf + count, size - count,
 928                            "frames:  %u\npackets: %u\nempty:   %u\n"
 929                            "errors:  %u\ninvalid: %u\n",
 930                            stream->stats.stream.nb_frames,
 931                            stream->stats.stream.nb_packets,
 932                            stream->stats.stream.nb_empty,
 933                            stream->stats.stream.nb_errors,
 934                            stream->stats.stream.nb_invalid);
 935         count += scnprintf(buf + count, size - count,
 936                            "pts: %u early, %u initial, %u ok\n",
 937                            stream->stats.stream.nb_pts_early,
 938                            stream->stats.stream.nb_pts_initial,
 939                            stream->stats.stream.nb_pts_constant);
 940         count += scnprintf(buf + count, size - count,
 941                            "scr: %u count ok, %u diff ok\n",
 942                            stream->stats.stream.nb_scr_count_ok,
 943                            stream->stats.stream.nb_scr_diffs_ok);
 944         count += scnprintf(buf + count, size - count,
 945                            "sof: %u <= sof <= %u, freq %u.%03u kHz\n",
 946                            stream->stats.stream.min_sof,
 947                            stream->stats.stream.max_sof,
 948                            scr_sof_freq / 1000, scr_sof_freq % 1000);
 949 
 950         return count;
 951 }
 952 
 953 static void uvc_video_stats_start(struct uvc_streaming *stream)
 954 {
 955         memset(&stream->stats, 0, sizeof(stream->stats));
 956         stream->stats.stream.min_sof = 2048;
 957 }
 958 
 959 static void uvc_video_stats_stop(struct uvc_streaming *stream)
 960 {
 961         stream->stats.stream.stop_ts = ktime_get();
 962 }
 963 
 964 /* ------------------------------------------------------------------------
 965  * Video codecs
 966  */
 967 
 968 /* Video payload decoding is handled by uvc_video_decode_start(),
 969  * uvc_video_decode_data() and uvc_video_decode_end().
 970  *
 971  * uvc_video_decode_start is called with URB data at the start of a bulk or
 972  * isochronous payload. It processes header data and returns the header size
 973  * in bytes if successful. If an error occurs, it returns a negative error
 974  * code. The following error codes have special meanings.
 975  *
 976  * - EAGAIN informs the caller that the current video buffer should be marked
 977  *   as done, and that the function should be called again with the same data
 978  *   and a new video buffer. This is used when end of frame conditions can be
 979  *   reliably detected at the beginning of the next frame only.
 980  *
 981  * If an error other than -EAGAIN is returned, the caller will drop the current
 982  * payload. No call to uvc_video_decode_data and uvc_video_decode_end will be
 983  * made until the next payload. -ENODATA can be used to drop the current
 984  * payload if no other error code is appropriate.
 985  *
 986  * uvc_video_decode_data is called for every URB with URB data. It copies the
 987  * data to the video buffer.
 988  *
 989  * uvc_video_decode_end is called with header data at the end of a bulk or
 990  * isochronous payload. It performs any additional header data processing and
 991  * returns 0 or a negative error code if an error occurred. As header data have
 992  * already been processed by uvc_video_decode_start, this functions isn't
 993  * required to perform sanity checks a second time.
 994  *
 995  * For isochronous transfers where a payload is always transferred in a single
 996  * URB, the three functions will be called in a row.
 997  *
 998  * To let the decoder process header data and update its internal state even
 999  * when no video buffer is available, uvc_video_decode_start must be prepared
1000  * to be called with a NULL buf parameter. uvc_video_decode_data and
1001  * uvc_video_decode_end will never be called with a NULL buffer.
1002  */
1003 static int uvc_video_decode_start(struct uvc_streaming *stream,
1004                 struct uvc_buffer *buf, const u8 *data, int len)
1005 {
1006         u8 fid;
1007 
1008         /* Sanity checks:
1009          * - packet must be at least 2 bytes long
1010          * - bHeaderLength value must be at least 2 bytes (see above)
1011          * - bHeaderLength value can't be larger than the packet size.
1012          */
1013         if (len < 2 || data[0] < 2 || data[0] > len) {
1014                 stream->stats.frame.nb_invalid++;
1015                 return -EINVAL;
1016         }
1017 
1018         fid = data[1] & UVC_STREAM_FID;
1019 
1020         /* Increase the sequence number regardless of any buffer states, so
1021          * that discontinuous sequence numbers always indicate lost frames.
1022          */
1023         if (stream->last_fid != fid) {
1024                 stream->sequence++;
1025                 if (stream->sequence)
1026                         uvc_video_stats_update(stream);
1027         }
1028 
1029         uvc_video_clock_decode(stream, buf, data, len);
1030         uvc_video_stats_decode(stream, data, len);
1031 
1032         /* Store the payload FID bit and return immediately when the buffer is
1033          * NULL.
1034          */
1035         if (buf == NULL) {
1036                 stream->last_fid = fid;
1037                 return -ENODATA;
1038         }
1039 
1040         /* Mark the buffer as bad if the error bit is set. */
1041         if (data[1] & UVC_STREAM_ERR) {
1042                 uvc_trace(UVC_TRACE_FRAME, "Marking buffer as bad (error bit "
1043                           "set).\n");
1044                 buf->error = 1;
1045         }
1046 
1047         /* Synchronize to the input stream by waiting for the FID bit to be
1048          * toggled when the the buffer state is not UVC_BUF_STATE_ACTIVE.
1049          * stream->last_fid is initialized to -1, so the first isochronous
1050          * frame will always be in sync.
1051          *
1052          * If the device doesn't toggle the FID bit, invert stream->last_fid
1053          * when the EOF bit is set to force synchronisation on the next packet.
1054          */
1055         if (buf->state != UVC_BUF_STATE_ACTIVE) {
1056                 if (fid == stream->last_fid) {
1057                         uvc_trace(UVC_TRACE_FRAME, "Dropping payload (out of "
1058                                 "sync).\n");
1059                         if ((stream->dev->quirks & UVC_QUIRK_STREAM_NO_FID) &&
1060                             (data[1] & UVC_STREAM_EOF))
1061                                 stream->last_fid ^= UVC_STREAM_FID;
1062                         return -ENODATA;
1063                 }
1064 
1065                 buf->buf.field = V4L2_FIELD_NONE;
1066                 buf->buf.sequence = stream->sequence;
1067                 buf->buf.vb2_buf.timestamp = ktime_to_ns(uvc_video_get_time());
1068 
1069                 /* TODO: Handle PTS and SCR. */
1070                 buf->state = UVC_BUF_STATE_ACTIVE;
1071         }
1072 
1073         /* Mark the buffer as done if we're at the beginning of a new frame.
1074          * End of frame detection is better implemented by checking the EOF
1075          * bit (FID bit toggling is delayed by one frame compared to the EOF
1076          * bit), but some devices don't set the bit at end of frame (and the
1077          * last payload can be lost anyway). We thus must check if the FID has
1078          * been toggled.
1079          *
1080          * stream->last_fid is initialized to -1, so the first isochronous
1081          * frame will never trigger an end of frame detection.
1082          *
1083          * Empty buffers (bytesused == 0) don't trigger end of frame detection
1084          * as it doesn't make sense to return an empty buffer. This also
1085          * avoids detecting end of frame conditions at FID toggling if the
1086          * previous payload had the EOF bit set.
1087          */
1088         if (fid != stream->last_fid && buf->bytesused != 0) {
1089                 uvc_trace(UVC_TRACE_FRAME, "Frame complete (FID bit "
1090                                 "toggled).\n");
1091                 buf->state = UVC_BUF_STATE_READY;
1092                 return -EAGAIN;
1093         }
1094 
1095         stream->last_fid = fid;
1096 
1097         return data[0];
1098 }
1099 
1100 /*
1101  * uvc_video_decode_data_work: Asynchronous memcpy processing
1102  *
1103  * Copy URB data to video buffers in process context, releasing buffer
1104  * references and requeuing the URB when done.
1105  */
1106 static void uvc_video_copy_data_work(struct work_struct *work)
1107 {
1108         struct uvc_urb *uvc_urb = container_of(work, struct uvc_urb, work);
1109         unsigned int i;
1110         int ret;
1111 
1112         for (i = 0; i < uvc_urb->async_operations; i++) {
1113                 struct uvc_copy_op *op = &uvc_urb->copy_operations[i];
1114 
1115                 memcpy(op->dst, op->src, op->len);
1116 
1117                 /* Release reference taken on this buffer. */
1118                 uvc_queue_buffer_release(op->buf);
1119         }
1120 
1121         ret = usb_submit_urb(uvc_urb->urb, GFP_KERNEL);
1122         if (ret < 0)
1123                 uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n",
1124                            ret);
1125 }
1126 
1127 static void uvc_video_decode_data(struct uvc_urb *uvc_urb,
1128                 struct uvc_buffer *buf, const u8 *data, int len)
1129 {
1130         unsigned int active_op = uvc_urb->async_operations;
1131         struct uvc_copy_op *op = &uvc_urb->copy_operations[active_op];
1132         unsigned int maxlen;
1133 
1134         if (len <= 0)
1135                 return;
1136 
1137         maxlen = buf->length - buf->bytesused;
1138 
1139         /* Take a buffer reference for async work. */
1140         kref_get(&buf->ref);
1141 
1142         op->buf = buf;
1143         op->src = data;
1144         op->dst = buf->mem + buf->bytesused;
1145         op->len = min_t(unsigned int, len, maxlen);
1146 
1147         buf->bytesused += op->len;
1148 
1149         /* Complete the current frame if the buffer size was exceeded. */
1150         if (len > maxlen) {
1151                 uvc_trace(UVC_TRACE_FRAME, "Frame complete (overflow).\n");
1152                 buf->error = 1;
1153                 buf->state = UVC_BUF_STATE_READY;
1154         }
1155 
1156         uvc_urb->async_operations++;
1157 }
1158 
1159 static void uvc_video_decode_end(struct uvc_streaming *stream,
1160                 struct uvc_buffer *buf, const u8 *data, int len)
1161 {
1162         /* Mark the buffer as done if the EOF marker is set. */
1163         if (data[1] & UVC_STREAM_EOF && buf->bytesused != 0) {
1164                 uvc_trace(UVC_TRACE_FRAME, "Frame complete (EOF found).\n");
1165                 if (data[0] == len)
1166                         uvc_trace(UVC_TRACE_FRAME, "EOF in empty payload.\n");
1167                 buf->state = UVC_BUF_STATE_READY;
1168                 if (stream->dev->quirks & UVC_QUIRK_STREAM_NO_FID)
1169                         stream->last_fid ^= UVC_STREAM_FID;
1170         }
1171 }
1172 
1173 /* Video payload encoding is handled by uvc_video_encode_header() and
1174  * uvc_video_encode_data(). Only bulk transfers are currently supported.
1175  *
1176  * uvc_video_encode_header is called at the start of a payload. It adds header
1177  * data to the transfer buffer and returns the header size. As the only known
1178  * UVC output device transfers a whole frame in a single payload, the EOF bit
1179  * is always set in the header.
1180  *
1181  * uvc_video_encode_data is called for every URB and copies the data from the
1182  * video buffer to the transfer buffer.
1183  */
1184 static int uvc_video_encode_header(struct uvc_streaming *stream,
1185                 struct uvc_buffer *buf, u8 *data, int len)
1186 {
1187         data[0] = 2;    /* Header length */
1188         data[1] = UVC_STREAM_EOH | UVC_STREAM_EOF
1189                 | (stream->last_fid & UVC_STREAM_FID);
1190         return 2;
1191 }
1192 
1193 static int uvc_video_encode_data(struct uvc_streaming *stream,
1194                 struct uvc_buffer *buf, u8 *data, int len)
1195 {
1196         struct uvc_video_queue *queue = &stream->queue;
1197         unsigned int nbytes;
1198         void *mem;
1199 
1200         /* Copy video data to the URB buffer. */
1201         mem = buf->mem + queue->buf_used;
1202         nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
1203         nbytes = min(stream->bulk.max_payload_size - stream->bulk.payload_size,
1204                         nbytes);
1205         memcpy(data, mem, nbytes);
1206 
1207         queue->buf_used += nbytes;
1208 
1209         return nbytes;
1210 }
1211 
1212 /* ------------------------------------------------------------------------
1213  * Metadata
1214  */
1215 
1216 /*
1217  * Additionally to the payload headers we also want to provide the user with USB
1218  * Frame Numbers and system time values. The resulting buffer is thus composed
1219  * of blocks, containing a 64-bit timestamp in  nanoseconds, a 16-bit USB Frame
1220  * Number, and a copy of the payload header.
1221  *
1222  * Ideally we want to capture all payload headers for each frame. However, their
1223  * number is unknown and unbound. We thus drop headers that contain no vendor
1224  * data and that either contain no SCR value or an SCR value identical to the
1225  * previous header.
1226  */
1227 static void uvc_video_decode_meta(struct uvc_streaming *stream,
1228                                   struct uvc_buffer *meta_buf,
1229                                   const u8 *mem, unsigned int length)
1230 {
1231         struct uvc_meta_buf *meta;
1232         size_t len_std = 2;
1233         bool has_pts, has_scr;
1234         unsigned long flags;
1235         unsigned int sof;
1236         ktime_t time;
1237         const u8 *scr;
1238 
1239         if (!meta_buf || length == 2)
1240                 return;
1241 
1242         if (meta_buf->length - meta_buf->bytesused <
1243             length + sizeof(meta->ns) + sizeof(meta->sof)) {
1244                 meta_buf->error = 1;
1245                 return;
1246         }
1247 
1248         has_pts = mem[1] & UVC_STREAM_PTS;
1249         has_scr = mem[1] & UVC_STREAM_SCR;
1250 
1251         if (has_pts) {
1252                 len_std += 4;
1253                 scr = mem + 6;
1254         } else {
1255                 scr = mem + 2;
1256         }
1257 
1258         if (has_scr)
1259                 len_std += 6;
1260 
1261         if (stream->meta.format == V4L2_META_FMT_UVC)
1262                 length = len_std;
1263 
1264         if (length == len_std && (!has_scr ||
1265                                   !memcmp(scr, stream->clock.last_scr, 6)))
1266                 return;
1267 
1268         meta = (struct uvc_meta_buf *)((u8 *)meta_buf->mem + meta_buf->bytesused);
1269         local_irq_save(flags);
1270         time = uvc_video_get_time();
1271         sof = usb_get_current_frame_number(stream->dev->udev);
1272         local_irq_restore(flags);
1273         put_unaligned(ktime_to_ns(time), &meta->ns);
1274         put_unaligned(sof, &meta->sof);
1275 
1276         if (has_scr)
1277                 memcpy(stream->clock.last_scr, scr, 6);
1278 
1279         memcpy(&meta->length, mem, length);
1280         meta_buf->bytesused += length + sizeof(meta->ns) + sizeof(meta->sof);
1281 
1282         uvc_trace(UVC_TRACE_FRAME,
1283                   "%s(): t-sys %lluns, SOF %u, len %u, flags 0x%x, PTS %u, STC %u frame SOF %u\n",
1284                   __func__, ktime_to_ns(time), meta->sof, meta->length,
1285                   meta->flags,
1286                   has_pts ? *(u32 *)meta->buf : 0,
1287                   has_scr ? *(u32 *)scr : 0,
1288                   has_scr ? *(u32 *)(scr + 4) & 0x7ff : 0);
1289 }
1290 
1291 /* ------------------------------------------------------------------------
1292  * URB handling
1293  */
1294 
1295 /*
1296  * Set error flag for incomplete buffer.
1297  */
1298 static void uvc_video_validate_buffer(const struct uvc_streaming *stream,
1299                                       struct uvc_buffer *buf)
1300 {
1301         if (stream->ctrl.dwMaxVideoFrameSize != buf->bytesused &&
1302             !(stream->cur_format->flags & UVC_FMT_FLAG_COMPRESSED))
1303                 buf->error = 1;
1304 }
1305 
1306 /*
1307  * Completion handler for video URBs.
1308  */
1309 
1310 static void uvc_video_next_buffers(struct uvc_streaming *stream,
1311                 struct uvc_buffer **video_buf, struct uvc_buffer **meta_buf)
1312 {
1313         uvc_video_validate_buffer(stream, *video_buf);
1314 
1315         if (*meta_buf) {
1316                 struct vb2_v4l2_buffer *vb2_meta = &(*meta_buf)->buf;
1317                 const struct vb2_v4l2_buffer *vb2_video = &(*video_buf)->buf;
1318 
1319                 vb2_meta->sequence = vb2_video->sequence;
1320                 vb2_meta->field = vb2_video->field;
1321                 vb2_meta->vb2_buf.timestamp = vb2_video->vb2_buf.timestamp;
1322 
1323                 (*meta_buf)->state = UVC_BUF_STATE_READY;
1324                 if (!(*meta_buf)->error)
1325                         (*meta_buf)->error = (*video_buf)->error;
1326                 *meta_buf = uvc_queue_next_buffer(&stream->meta.queue,
1327                                                   *meta_buf);
1328         }
1329         *video_buf = uvc_queue_next_buffer(&stream->queue, *video_buf);
1330 }
1331 
1332 static void uvc_video_decode_isoc(struct uvc_urb *uvc_urb,
1333                         struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1334 {
1335         struct urb *urb = uvc_urb->urb;
1336         struct uvc_streaming *stream = uvc_urb->stream;
1337         u8 *mem;
1338         int ret, i;
1339 
1340         for (i = 0; i < urb->number_of_packets; ++i) {
1341                 if (urb->iso_frame_desc[i].status < 0) {
1342                         uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
1343                                 "lost (%d).\n", urb->iso_frame_desc[i].status);
1344                         /* Mark the buffer as faulty. */
1345                         if (buf != NULL)
1346                                 buf->error = 1;
1347                         continue;
1348                 }
1349 
1350                 /* Decode the payload header. */
1351                 mem = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
1352                 do {
1353                         ret = uvc_video_decode_start(stream, buf, mem,
1354                                 urb->iso_frame_desc[i].actual_length);
1355                         if (ret == -EAGAIN)
1356                                 uvc_video_next_buffers(stream, &buf, &meta_buf);
1357                 } while (ret == -EAGAIN);
1358 
1359                 if (ret < 0)
1360                         continue;
1361 
1362                 uvc_video_decode_meta(stream, meta_buf, mem, ret);
1363 
1364                 /* Decode the payload data. */
1365                 uvc_video_decode_data(uvc_urb, buf, mem + ret,
1366                         urb->iso_frame_desc[i].actual_length - ret);
1367 
1368                 /* Process the header again. */
1369                 uvc_video_decode_end(stream, buf, mem,
1370                         urb->iso_frame_desc[i].actual_length);
1371 
1372                 if (buf->state == UVC_BUF_STATE_READY)
1373                         uvc_video_next_buffers(stream, &buf, &meta_buf);
1374         }
1375 }
1376 
1377 static void uvc_video_decode_bulk(struct uvc_urb *uvc_urb,
1378                         struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1379 {
1380         struct urb *urb = uvc_urb->urb;
1381         struct uvc_streaming *stream = uvc_urb->stream;
1382         u8 *mem;
1383         int len, ret;
1384 
1385         /*
1386          * Ignore ZLPs if they're not part of a frame, otherwise process them
1387          * to trigger the end of payload detection.
1388          */
1389         if (urb->actual_length == 0 && stream->bulk.header_size == 0)
1390                 return;
1391 
1392         mem = urb->transfer_buffer;
1393         len = urb->actual_length;
1394         stream->bulk.payload_size += len;
1395 
1396         /* If the URB is the first of its payload, decode and save the
1397          * header.
1398          */
1399         if (stream->bulk.header_size == 0 && !stream->bulk.skip_payload) {
1400                 do {
1401                         ret = uvc_video_decode_start(stream, buf, mem, len);
1402                         if (ret == -EAGAIN)
1403                                 uvc_video_next_buffers(stream, &buf, &meta_buf);
1404                 } while (ret == -EAGAIN);
1405 
1406                 /* If an error occurred skip the rest of the payload. */
1407                 if (ret < 0 || buf == NULL) {
1408                         stream->bulk.skip_payload = 1;
1409                 } else {
1410                         memcpy(stream->bulk.header, mem, ret);
1411                         stream->bulk.header_size = ret;
1412 
1413                         uvc_video_decode_meta(stream, meta_buf, mem, ret);
1414 
1415                         mem += ret;
1416                         len -= ret;
1417                 }
1418         }
1419 
1420         /* The buffer queue might have been cancelled while a bulk transfer
1421          * was in progress, so we can reach here with buf equal to NULL. Make
1422          * sure buf is never dereferenced if NULL.
1423          */
1424 
1425         /* Prepare video data for processing. */
1426         if (!stream->bulk.skip_payload && buf != NULL)
1427                 uvc_video_decode_data(uvc_urb, buf, mem, len);
1428 
1429         /* Detect the payload end by a URB smaller than the maximum size (or
1430          * a payload size equal to the maximum) and process the header again.
1431          */
1432         if (urb->actual_length < urb->transfer_buffer_length ||
1433             stream->bulk.payload_size >= stream->bulk.max_payload_size) {
1434                 if (!stream->bulk.skip_payload && buf != NULL) {
1435                         uvc_video_decode_end(stream, buf, stream->bulk.header,
1436                                 stream->bulk.payload_size);
1437                         if (buf->state == UVC_BUF_STATE_READY)
1438                                 uvc_video_next_buffers(stream, &buf, &meta_buf);
1439                 }
1440 
1441                 stream->bulk.header_size = 0;
1442                 stream->bulk.skip_payload = 0;
1443                 stream->bulk.payload_size = 0;
1444         }
1445 }
1446 
1447 static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb,
1448         struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1449 {
1450         struct urb *urb = uvc_urb->urb;
1451         struct uvc_streaming *stream = uvc_urb->stream;
1452 
1453         u8 *mem = urb->transfer_buffer;
1454         int len = stream->urb_size, ret;
1455 
1456         if (buf == NULL) {
1457                 urb->transfer_buffer_length = 0;
1458                 return;
1459         }
1460 
1461         /* If the URB is the first of its payload, add the header. */
1462         if (stream->bulk.header_size == 0) {
1463                 ret = uvc_video_encode_header(stream, buf, mem, len);
1464                 stream->bulk.header_size = ret;
1465                 stream->bulk.payload_size += ret;
1466                 mem += ret;
1467                 len -= ret;
1468         }
1469 
1470         /* Process video data. */
1471         ret = uvc_video_encode_data(stream, buf, mem, len);
1472 
1473         stream->bulk.payload_size += ret;
1474         len -= ret;
1475 
1476         if (buf->bytesused == stream->queue.buf_used ||
1477             stream->bulk.payload_size == stream->bulk.max_payload_size) {
1478                 if (buf->bytesused == stream->queue.buf_used) {
1479                         stream->queue.buf_used = 0;
1480                         buf->state = UVC_BUF_STATE_READY;
1481                         buf->buf.sequence = ++stream->sequence;
1482                         uvc_queue_next_buffer(&stream->queue, buf);
1483                         stream->last_fid ^= UVC_STREAM_FID;
1484                 }
1485 
1486                 stream->bulk.header_size = 0;
1487                 stream->bulk.payload_size = 0;
1488         }
1489 
1490         urb->transfer_buffer_length = stream->urb_size - len;
1491 }
1492 
1493 static void uvc_video_complete(struct urb *urb)
1494 {
1495         struct uvc_urb *uvc_urb = urb->context;
1496         struct uvc_streaming *stream = uvc_urb->stream;
1497         struct uvc_video_queue *queue = &stream->queue;
1498         struct uvc_video_queue *qmeta = &stream->meta.queue;
1499         struct vb2_queue *vb2_qmeta = stream->meta.vdev.queue;
1500         struct uvc_buffer *buf = NULL;
1501         struct uvc_buffer *buf_meta = NULL;
1502         unsigned long flags;
1503         int ret;
1504 
1505         switch (urb->status) {
1506         case 0:
1507                 break;
1508 
1509         default:
1510                 uvc_printk(KERN_WARNING, "Non-zero status (%d) in video "
1511                         "completion handler.\n", urb->status);
1512                 /* fall through */
1513         case -ENOENT:           /* usb_poison_urb() called. */
1514                 if (stream->frozen)
1515                         return;
1516                 /* fall through */
1517         case -ECONNRESET:       /* usb_unlink_urb() called. */
1518         case -ESHUTDOWN:        /* The endpoint is being disabled. */
1519                 uvc_queue_cancel(queue, urb->status == -ESHUTDOWN);
1520                 if (vb2_qmeta)
1521                         uvc_queue_cancel(qmeta, urb->status == -ESHUTDOWN);
1522                 return;
1523         }
1524 
1525         buf = uvc_queue_get_current_buffer(queue);
1526 
1527         if (vb2_qmeta) {
1528                 spin_lock_irqsave(&qmeta->irqlock, flags);
1529                 if (!list_empty(&qmeta->irqqueue))
1530                         buf_meta = list_first_entry(&qmeta->irqqueue,
1531                                                     struct uvc_buffer, queue);
1532                 spin_unlock_irqrestore(&qmeta->irqlock, flags);
1533         }
1534 
1535         /* Re-initialise the URB async work. */
1536         uvc_urb->async_operations = 0;
1537 
1538         /*
1539          * Process the URB headers, and optionally queue expensive memcpy tasks
1540          * to be deferred to a work queue.
1541          */
1542         stream->decode(uvc_urb, buf, buf_meta);
1543 
1544         /* If no async work is needed, resubmit the URB immediately. */
1545         if (!uvc_urb->async_operations) {
1546                 ret = usb_submit_urb(uvc_urb->urb, GFP_ATOMIC);
1547                 if (ret < 0)
1548                         uvc_printk(KERN_ERR,
1549                                    "Failed to resubmit video URB (%d).\n",
1550                                    ret);
1551                 return;
1552         }
1553 
1554         queue_work(stream->async_wq, &uvc_urb->work);
1555 }
1556 
1557 /*
1558  * Free transfer buffers.
1559  */
1560 static void uvc_free_urb_buffers(struct uvc_streaming *stream)
1561 {
1562         struct uvc_urb *uvc_urb;
1563 
1564         for_each_uvc_urb(uvc_urb, stream) {
1565                 if (!uvc_urb->buffer)
1566                         continue;
1567 
1568 #ifndef CONFIG_DMA_NONCOHERENT
1569                 usb_free_coherent(stream->dev->udev, stream->urb_size,
1570                                   uvc_urb->buffer, uvc_urb->dma);
1571 #else
1572                 kfree(uvc_urb->buffer);
1573 #endif
1574                 uvc_urb->buffer = NULL;
1575         }
1576 
1577         stream->urb_size = 0;
1578 }
1579 
1580 /*
1581  * Allocate transfer buffers. This function can be called with buffers
1582  * already allocated when resuming from suspend, in which case it will
1583  * return without touching the buffers.
1584  *
1585  * Limit the buffer size to UVC_MAX_PACKETS bulk/isochronous packets. If the
1586  * system is too low on memory try successively smaller numbers of packets
1587  * until allocation succeeds.
1588  *
1589  * Return the number of allocated packets on success or 0 when out of memory.
1590  */
1591 static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
1592         unsigned int size, unsigned int psize, gfp_t gfp_flags)
1593 {
1594         unsigned int npackets;
1595         unsigned int i;
1596 
1597         /* Buffers are already allocated, bail out. */
1598         if (stream->urb_size)
1599                 return stream->urb_size / psize;
1600 
1601         /* Compute the number of packets. Bulk endpoints might transfer UVC
1602          * payloads across multiple URBs.
1603          */
1604         npackets = DIV_ROUND_UP(size, psize);
1605         if (npackets > UVC_MAX_PACKETS)
1606                 npackets = UVC_MAX_PACKETS;
1607 
1608         /* Retry allocations until one succeed. */
1609         for (; npackets > 1; npackets /= 2) {
1610                 for (i = 0; i < UVC_URBS; ++i) {
1611                         struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
1612 
1613                         stream->urb_size = psize * npackets;
1614 #ifndef CONFIG_DMA_NONCOHERENT
1615                         uvc_urb->buffer = usb_alloc_coherent(
1616                                 stream->dev->udev, stream->urb_size,
1617                                 gfp_flags | __GFP_NOWARN, &uvc_urb->dma);
1618 #else
1619                         uvc_urb->buffer =
1620                             kmalloc(stream->urb_size, gfp_flags | __GFP_NOWARN);
1621 #endif
1622                         if (!uvc_urb->buffer) {
1623                                 uvc_free_urb_buffers(stream);
1624                                 break;
1625                         }
1626 
1627                         uvc_urb->stream = stream;
1628                 }
1629 
1630                 if (i == UVC_URBS) {
1631                         uvc_trace(UVC_TRACE_VIDEO, "Allocated %u URB buffers "
1632                                 "of %ux%u bytes each.\n", UVC_URBS, npackets,
1633                                 psize);
1634                         return npackets;
1635                 }
1636         }
1637 
1638         uvc_trace(UVC_TRACE_VIDEO, "Failed to allocate URB buffers (%u bytes "
1639                 "per packet).\n", psize);
1640         return 0;
1641 }
1642 
1643 /*
1644  * Uninitialize isochronous/bulk URBs and free transfer buffers.
1645  */
1646 static void uvc_video_stop_transfer(struct uvc_streaming *stream,
1647                                     int free_buffers)
1648 {
1649         struct uvc_urb *uvc_urb;
1650 
1651         uvc_video_stats_stop(stream);
1652 
1653         /*
1654          * We must poison the URBs rather than kill them to ensure that even
1655          * after the completion handler returns, any asynchronous workqueues
1656          * will be prevented from resubmitting the URBs.
1657          */
1658         for_each_uvc_urb(uvc_urb, stream)
1659                 usb_poison_urb(uvc_urb->urb);
1660 
1661         flush_workqueue(stream->async_wq);
1662 
1663         for_each_uvc_urb(uvc_urb, stream) {
1664                 usb_free_urb(uvc_urb->urb);
1665                 uvc_urb->urb = NULL;
1666         }
1667 
1668         if (free_buffers)
1669                 uvc_free_urb_buffers(stream);
1670 }
1671 
1672 /*
1673  * Compute the maximum number of bytes per interval for an endpoint.
1674  */
1675 static unsigned int uvc_endpoint_max_bpi(struct usb_device *dev,
1676                                          struct usb_host_endpoint *ep)
1677 {
1678         u16 psize;
1679         u16 mult;
1680 
1681         switch (dev->speed) {
1682         case USB_SPEED_SUPER:
1683         case USB_SPEED_SUPER_PLUS:
1684                 return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
1685         case USB_SPEED_HIGH:
1686                 psize = usb_endpoint_maxp(&ep->desc);
1687                 mult = usb_endpoint_maxp_mult(&ep->desc);
1688                 return psize * mult;
1689         case USB_SPEED_WIRELESS:
1690                 psize = usb_endpoint_maxp(&ep->desc);
1691                 return psize;
1692         default:
1693                 psize = usb_endpoint_maxp(&ep->desc);
1694                 return psize;
1695         }
1696 }
1697 
1698 /*
1699  * Initialize isochronous URBs and allocate transfer buffers. The packet size
1700  * is given by the endpoint.
1701  */
1702 static int uvc_init_video_isoc(struct uvc_streaming *stream,
1703         struct usb_host_endpoint *ep, gfp_t gfp_flags)
1704 {
1705         struct urb *urb;
1706         struct uvc_urb *uvc_urb;
1707         unsigned int npackets, i;
1708         u16 psize;
1709         u32 size;
1710 
1711         psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
1712         size = stream->ctrl.dwMaxVideoFrameSize;
1713 
1714         npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
1715         if (npackets == 0)
1716                 return -ENOMEM;
1717 
1718         size = npackets * psize;
1719 
1720         for_each_uvc_urb(uvc_urb, stream) {
1721                 urb = usb_alloc_urb(npackets, gfp_flags);
1722                 if (urb == NULL) {
1723                         uvc_video_stop_transfer(stream, 1);
1724                         return -ENOMEM;
1725                 }
1726 
1727                 urb->dev = stream->dev->udev;
1728                 urb->context = uvc_urb;
1729                 urb->pipe = usb_rcvisocpipe(stream->dev->udev,
1730                                 ep->desc.bEndpointAddress);
1731 #ifndef CONFIG_DMA_NONCOHERENT
1732                 urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
1733                 urb->transfer_dma = uvc_urb->dma;
1734 #else
1735                 urb->transfer_flags = URB_ISO_ASAP;
1736 #endif
1737                 urb->interval = ep->desc.bInterval;
1738                 urb->transfer_buffer = uvc_urb->buffer;
1739                 urb->complete = uvc_video_complete;
1740                 urb->number_of_packets = npackets;
1741                 urb->transfer_buffer_length = size;
1742 
1743                 for (i = 0; i < npackets; ++i) {
1744                         urb->iso_frame_desc[i].offset = i * psize;
1745                         urb->iso_frame_desc[i].length = psize;
1746                 }
1747 
1748                 uvc_urb->urb = urb;
1749         }
1750 
1751         return 0;
1752 }
1753 
1754 /*
1755  * Initialize bulk URBs and allocate transfer buffers. The packet size is
1756  * given by the endpoint.
1757  */
1758 static int uvc_init_video_bulk(struct uvc_streaming *stream,
1759         struct usb_host_endpoint *ep, gfp_t gfp_flags)
1760 {
1761         struct urb *urb;
1762         struct uvc_urb *uvc_urb;
1763         unsigned int npackets, pipe;
1764         u16 psize;
1765         u32 size;
1766 
1767         psize = usb_endpoint_maxp(&ep->desc);
1768         size = stream->ctrl.dwMaxPayloadTransferSize;
1769         stream->bulk.max_payload_size = size;
1770 
1771         npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
1772         if (npackets == 0)
1773                 return -ENOMEM;
1774 
1775         size = npackets * psize;
1776 
1777         if (usb_endpoint_dir_in(&ep->desc))
1778                 pipe = usb_rcvbulkpipe(stream->dev->udev,
1779                                        ep->desc.bEndpointAddress);
1780         else
1781                 pipe = usb_sndbulkpipe(stream->dev->udev,
1782                                        ep->desc.bEndpointAddress);
1783 
1784         if (stream->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
1785                 size = 0;
1786 
1787         for_each_uvc_urb(uvc_urb, stream) {
1788                 urb = usb_alloc_urb(0, gfp_flags);
1789                 if (urb == NULL) {
1790                         uvc_video_stop_transfer(stream, 1);
1791                         return -ENOMEM;
1792                 }
1793 
1794                 usb_fill_bulk_urb(urb, stream->dev->udev, pipe, uvc_urb->buffer,
1795                                   size, uvc_video_complete, uvc_urb);
1796 #ifndef CONFIG_DMA_NONCOHERENT
1797                 urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1798                 urb->transfer_dma = uvc_urb->dma;
1799 #endif
1800 
1801                 uvc_urb->urb = urb;
1802         }
1803 
1804         return 0;
1805 }
1806 
1807 /*
1808  * Initialize isochronous/bulk URBs and allocate transfer buffers.
1809  */
1810 static int uvc_video_start_transfer(struct uvc_streaming *stream,
1811                                     gfp_t gfp_flags)
1812 {
1813         struct usb_interface *intf = stream->intf;
1814         struct usb_host_endpoint *ep;
1815         struct uvc_urb *uvc_urb;
1816         unsigned int i;
1817         int ret;
1818 
1819         stream->sequence = -1;
1820         stream->last_fid = -1;
1821         stream->bulk.header_size = 0;
1822         stream->bulk.skip_payload = 0;
1823         stream->bulk.payload_size = 0;
1824 
1825         uvc_video_stats_start(stream);
1826 
1827         if (intf->num_altsetting > 1) {
1828                 struct usb_host_endpoint *best_ep = NULL;
1829                 unsigned int best_psize = UINT_MAX;
1830                 unsigned int bandwidth;
1831                 unsigned int uninitialized_var(altsetting);
1832                 int intfnum = stream->intfnum;
1833 
1834                 /* Isochronous endpoint, select the alternate setting. */
1835                 bandwidth = stream->ctrl.dwMaxPayloadTransferSize;
1836 
1837                 if (bandwidth == 0) {
1838                         uvc_trace(UVC_TRACE_VIDEO, "Device requested null "
1839                                 "bandwidth, defaulting to lowest.\n");
1840                         bandwidth = 1;
1841                 } else {
1842                         uvc_trace(UVC_TRACE_VIDEO, "Device requested %u "
1843                                 "B/frame bandwidth.\n", bandwidth);
1844                 }
1845 
1846                 for (i = 0; i < intf->num_altsetting; ++i) {
1847                         struct usb_host_interface *alts;
1848                         unsigned int psize;
1849 
1850                         alts = &intf->altsetting[i];
1851                         ep = uvc_find_endpoint(alts,
1852                                 stream->header.bEndpointAddress);
1853                         if (ep == NULL)
1854                                 continue;
1855 
1856                         /* Check if the bandwidth is high enough. */
1857                         psize = uvc_endpoint_max_bpi(stream->dev->udev, ep);
1858                         if (psize >= bandwidth && psize <= best_psize) {
1859                                 altsetting = alts->desc.bAlternateSetting;
1860                                 best_psize = psize;
1861                                 best_ep = ep;
1862                         }
1863                 }
1864 
1865                 if (best_ep == NULL) {
1866                         uvc_trace(UVC_TRACE_VIDEO, "No fast enough alt setting "
1867                                 "for requested bandwidth.\n");
1868                         return -EIO;
1869                 }
1870 
1871                 uvc_trace(UVC_TRACE_VIDEO, "Selecting alternate setting %u "
1872                         "(%u B/frame bandwidth).\n", altsetting, best_psize);
1873 
1874                 ret = usb_set_interface(stream->dev->udev, intfnum, altsetting);
1875                 if (ret < 0)
1876                         return ret;
1877 
1878                 ret = uvc_init_video_isoc(stream, best_ep, gfp_flags);
1879         } else {
1880                 /* Bulk endpoint, proceed to URB initialization. */
1881                 ep = uvc_find_endpoint(&intf->altsetting[0],
1882                                 stream->header.bEndpointAddress);
1883                 if (ep == NULL)
1884                         return -EIO;
1885 
1886                 ret = uvc_init_video_bulk(stream, ep, gfp_flags);
1887         }
1888 
1889         if (ret < 0)
1890                 return ret;
1891 
1892         /* Submit the URBs. */
1893         for_each_uvc_urb(uvc_urb, stream) {
1894                 ret = usb_submit_urb(uvc_urb->urb, gfp_flags);
1895                 if (ret < 0) {
1896                         uvc_printk(KERN_ERR, "Failed to submit URB %u (%d).\n",
1897                                    uvc_urb_index(uvc_urb), ret);
1898                         uvc_video_stop_transfer(stream, 1);
1899                         return ret;
1900                 }
1901         }
1902 
1903         /* The Logitech C920 temporarily forgets that it should not be adjusting
1904          * Exposure Absolute during init so restore controls to stored values.
1905          */
1906         if (stream->dev->quirks & UVC_QUIRK_RESTORE_CTRLS_ON_INIT)
1907                 uvc_ctrl_restore_values(stream->dev);
1908 
1909         return 0;
1910 }
1911 
1912 /* --------------------------------------------------------------------------
1913  * Suspend/resume
1914  */
1915 
1916 /*
1917  * Stop streaming without disabling the video queue.
1918  *
1919  * To let userspace applications resume without trouble, we must not touch the
1920  * video buffers in any way. We mark the device as frozen to make sure the URB
1921  * completion handler won't try to cancel the queue when we kill the URBs.
1922  */
1923 int uvc_video_suspend(struct uvc_streaming *stream)
1924 {
1925         if (!uvc_queue_streaming(&stream->queue))
1926                 return 0;
1927 
1928         stream->frozen = 1;
1929         uvc_video_stop_transfer(stream, 0);
1930         usb_set_interface(stream->dev->udev, stream->intfnum, 0);
1931         return 0;
1932 }
1933 
1934 /*
1935  * Reconfigure the video interface and restart streaming if it was enabled
1936  * before suspend.
1937  *
1938  * If an error occurs, disable the video queue. This will wake all pending
1939  * buffers, making sure userspace applications are notified of the problem
1940  * instead of waiting forever.
1941  */
1942 int uvc_video_resume(struct uvc_streaming *stream, int reset)
1943 {
1944         int ret;
1945 
1946         /* If the bus has been reset on resume, set the alternate setting to 0.
1947          * This should be the default value, but some devices crash or otherwise
1948          * misbehave if they don't receive a SET_INTERFACE request before any
1949          * other video control request.
1950          */
1951         if (reset)
1952                 usb_set_interface(stream->dev->udev, stream->intfnum, 0);
1953 
1954         stream->frozen = 0;
1955 
1956         uvc_video_clock_reset(stream);
1957 
1958         if (!uvc_queue_streaming(&stream->queue))
1959                 return 0;
1960 
1961         ret = uvc_commit_video(stream, &stream->ctrl);
1962         if (ret < 0)
1963                 return ret;
1964 
1965         return uvc_video_start_transfer(stream, GFP_NOIO);
1966 }
1967 
1968 /* ------------------------------------------------------------------------
1969  * Video device
1970  */
1971 
1972 /*
1973  * Initialize the UVC video device by switching to alternate setting 0 and
1974  * retrieve the default format.
1975  *
1976  * Some cameras (namely the Fuji Finepix) set the format and frame
1977  * indexes to zero. The UVC standard doesn't clearly make this a spec
1978  * violation, so try to silently fix the values if possible.
1979  *
1980  * This function is called before registering the device with V4L.
1981  */
1982 int uvc_video_init(struct uvc_streaming *stream)
1983 {
1984         struct uvc_streaming_control *probe = &stream->ctrl;
1985         struct uvc_format *format = NULL;
1986         struct uvc_frame *frame = NULL;
1987         struct uvc_urb *uvc_urb;
1988         unsigned int i;
1989         int ret;
1990 
1991         if (stream->nformats == 0) {
1992                 uvc_printk(KERN_INFO, "No supported video formats found.\n");
1993                 return -EINVAL;
1994         }
1995 
1996         atomic_set(&stream->active, 0);
1997 
1998         /* Alternate setting 0 should be the default, yet the XBox Live Vision
1999          * Cam (and possibly other devices) crash or otherwise misbehave if
2000          * they don't receive a SET_INTERFACE request before any other video
2001          * control request.
2002          */
2003         usb_set_interface(stream->dev->udev, stream->intfnum, 0);
2004 
2005         /* Set the streaming probe control with default streaming parameters
2006          * retrieved from the device. Webcams that don't support GET_DEF
2007          * requests on the probe control will just keep their current streaming
2008          * parameters.
2009          */
2010         if (uvc_get_video_ctrl(stream, probe, 1, UVC_GET_DEF) == 0)
2011                 uvc_set_video_ctrl(stream, probe, 1);
2012 
2013         /* Initialize the streaming parameters with the probe control current
2014          * value. This makes sure SET_CUR requests on the streaming commit
2015          * control will always use values retrieved from a successful GET_CUR
2016          * request on the probe control, as required by the UVC specification.
2017          */
2018         ret = uvc_get_video_ctrl(stream, probe, 1, UVC_GET_CUR);
2019         if (ret < 0)
2020                 return ret;
2021 
2022         /* Check if the default format descriptor exists. Use the first
2023          * available format otherwise.
2024          */
2025         for (i = stream->nformats; i > 0; --i) {
2026                 format = &stream->format[i-1];
2027                 if (format->index == probe->bFormatIndex)
2028                         break;
2029         }
2030 
2031         if (format->nframes == 0) {
2032                 uvc_printk(KERN_INFO, "No frame descriptor found for the "
2033                         "default format.\n");
2034                 return -EINVAL;
2035         }
2036 
2037         /* Zero bFrameIndex might be correct. Stream-based formats (including
2038          * MPEG-2 TS and DV) do not support frames but have a dummy frame
2039          * descriptor with bFrameIndex set to zero. If the default frame
2040          * descriptor is not found, use the first available frame.
2041          */
2042         for (i = format->nframes; i > 0; --i) {
2043                 frame = &format->frame[i-1];
2044                 if (frame->bFrameIndex == probe->bFrameIndex)
2045                         break;
2046         }
2047 
2048         probe->bFormatIndex = format->index;
2049         probe->bFrameIndex = frame->bFrameIndex;
2050 
2051         stream->def_format = format;
2052         stream->cur_format = format;
2053         stream->cur_frame = frame;
2054 
2055         /* Select the video decoding function */
2056         if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
2057                 if (stream->dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)
2058                         stream->decode = uvc_video_decode_isight;
2059                 else if (stream->intf->num_altsetting > 1)
2060                         stream->decode = uvc_video_decode_isoc;
2061                 else
2062                         stream->decode = uvc_video_decode_bulk;
2063         } else {
2064                 if (stream->intf->num_altsetting == 1)
2065                         stream->decode = uvc_video_encode_bulk;
2066                 else {
2067                         uvc_printk(KERN_INFO, "Isochronous endpoints are not "
2068                                 "supported for video output devices.\n");
2069                         return -EINVAL;
2070                 }
2071         }
2072 
2073         /* Prepare asynchronous work items. */
2074         for_each_uvc_urb(uvc_urb, stream)
2075                 INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work);
2076 
2077         return 0;
2078 }
2079 
2080 int uvc_video_start_streaming(struct uvc_streaming *stream)
2081 {
2082         int ret;
2083 
2084         ret = uvc_video_clock_init(stream);
2085         if (ret < 0)
2086                 return ret;
2087 
2088         /* Commit the streaming parameters. */
2089         ret = uvc_commit_video(stream, &stream->ctrl);
2090         if (ret < 0)
2091                 goto error_commit;
2092 
2093         ret = uvc_video_start_transfer(stream, GFP_KERNEL);
2094         if (ret < 0)
2095                 goto error_video;
2096 
2097         return 0;
2098 
2099 error_video:
2100         usb_set_interface(stream->dev->udev, stream->intfnum, 0);
2101 error_commit:
2102         uvc_video_clock_cleanup(stream);
2103 
2104         return ret;
2105 }
2106 
2107 void uvc_video_stop_streaming(struct uvc_streaming *stream)
2108 {
2109         uvc_video_stop_transfer(stream, 1);
2110 
2111         if (stream->intf->num_altsetting > 1) {
2112                 usb_set_interface(stream->dev->udev, stream->intfnum, 0);
2113         } else {
2114                 /* UVC doesn't specify how to inform a bulk-based device
2115                  * when the video stream is stopped. Windows sends a
2116                  * CLEAR_FEATURE(HALT) request to the video streaming
2117                  * bulk endpoint, mimic the same behaviour.
2118                  */
2119                 unsigned int epnum = stream->header.bEndpointAddress
2120                                    & USB_ENDPOINT_NUMBER_MASK;
2121                 unsigned int dir = stream->header.bEndpointAddress
2122                                  & USB_ENDPOINT_DIR_MASK;
2123                 unsigned int pipe;
2124 
2125                 pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir;
2126                 usb_clear_halt(stream->dev->udev, pipe);
2127         }
2128 
2129         uvc_video_clock_cleanup(stream);
2130 }