drivers/usb/gadget/function/uvc_video.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      uvc_video.c  --  USB Video Class Gadget driver
   4  *
   5  *      Copyright (C) 2009-2010
   6  *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/device.h>
  11 #include <linux/errno.h>
  12 #include <linux/usb/ch9.h>
  13 #include <linux/usb/gadget.h>
  14 #include <linux/usb/video.h>
  15 #include <asm/unaligned.h>
  16
  17 #include <media/v4l2-dev.h>
  18
  19 #include "uvc.h"
  20 #include "uvc_queue.h"
  21 #include "uvc_video.h"
  22
  23 /* --------------------------------------------------------------------------
  24  * Video codecs
  25  */
  26
  27 static int
  28 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
  29                 u8 *data, int len)
  30 {
  31         struct uvc_device *uvc = container_of(video, struct uvc_device, video);
  32         struct usb_composite_dev *cdev = uvc->func.config->cdev;
  33         struct timespec64 ts = ns_to_timespec64(buf->buf.vb2_buf.timestamp);
  34         int pos = 2;
  35
  36         data[1] = UVC_STREAM_EOH | video->fid;
  37
  38         if (video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE)
  39                 data[1] |= UVC_STREAM_ERR;
  40
  41         if (video->queue.buf_used == 0 && ts.tv_sec) {
  42                 /* dwClockFrequency is 48 MHz */
  43                 u32 pts = ((u64)ts.tv_sec * USEC_PER_SEC + ts.tv_nsec / NSEC_PER_USEC) * 48;
  44
  45                 data[1] |= UVC_STREAM_PTS;
  46                 put_unaligned_le32(pts, &data[pos]);
  47                 pos += 4;
  48         }
  49
  50         if (cdev->gadget->ops->get_frame) {
  51                 u32 sof, stc;
  52
  53                 sof = usb_gadget_frame_number(cdev->gadget);
  54                 ktime_get_ts64(&ts);
  55                 stc = ((u64)ts.tv_sec * USEC_PER_SEC + ts.tv_nsec / NSEC_PER_USEC) * 48;
  56
  57                 data[1] |= UVC_STREAM_SCR;
  58                 put_unaligned_le32(stc, &data[pos]);
  59                 put_unaligned_le16(sof, &data[pos+4]);
  60                 pos += 6;
  61         }
  62
  63         data[0] = pos;
  64
  65         if (buf->bytesused - video->queue.buf_used <= len - pos)
  66                 data[1] |= UVC_STREAM_EOF;
  67
  68         return pos;
  69 }
  70
  71 static int
  72 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
  73                 u8 *data, int len)
  74 {
  75         struct uvc_video_queue *queue = &video->queue;
  76         unsigned int nbytes;
  77         void *mem;
  78
  79         /* Copy video data to the USB buffer. */
  80         mem = buf->mem + queue->buf_used;
  81         nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
  82
  83         memcpy(data, mem, nbytes);
  84         queue->buf_used += nbytes;
  85
  86         return nbytes;
  87 }
  88
  89 static void
  90 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
  91                 struct uvc_buffer *buf)
  92 {
  93         void *mem = req->buf;
  94         struct uvc_request *ureq = req->context;
  95         int len = video->req_size;
  96         int ret;
  97
  98         /* Add a header at the beginning of the payload. */
  99         if (video->payload_size == 0) {
 100                 ret = uvc_video_encode_header(video, buf, mem, len);
 101                 video->payload_size += ret;
 102                 mem += ret;
 103                 len -= ret;
 104         }
 105
 106         /* Process video data. */
 107         len = min((int)(video->max_payload_size - video->payload_size), len);
 108         ret = uvc_video_encode_data(video, buf, mem, len);
 109
 110         video->payload_size += ret;
 111         len -= ret;
 112
 113         req->length = video->req_size - len;
 114         req->zero = video->payload_size == video->max_payload_size;
 115
 116         if (buf->bytesused == video->queue.buf_used) {
 117                 video->queue.buf_used = 0;
 118                 buf->state = UVC_BUF_STATE_DONE;
 119                 list_del(&buf->queue);
 120                 video->fid ^= UVC_STREAM_FID;
 121                 ureq->last_buf = buf;
 122
 123                 video->payload_size = 0;
 124         }
 125
 126         if (video->payload_size == video->max_payload_size ||
 127             video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE ||
 128             buf->bytesused == video->queue.buf_used)
 129                 video->payload_size = 0;
 130 }
 131
 132 static void
 133 uvc_video_encode_isoc_sg(struct usb_request *req, struct uvc_video *video,
 134                 struct uvc_buffer *buf)
 135 {
 136         unsigned int pending = buf->bytesused - video->queue.buf_used;
 137         struct uvc_request *ureq = req->context;
 138         struct scatterlist *sg, *iter;
 139         unsigned int len = video->req_size;
 140         unsigned int sg_left, part = 0;
 141         unsigned int i;
 142         int header_len;
 143
 144         sg = ureq->sgt.sgl;
 145         sg_init_table(sg, ureq->sgt.nents);
 146
 147         /* Init the header. */
 148         header_len = uvc_video_encode_header(video, buf, ureq->header,
 149                                       video->req_size);
 150         sg_set_buf(sg, ureq->header, header_len);
 151         len -= header_len;
 152
 153         if (pending <= len)
 154                 len = pending;
 155
 156         req->length = (len == pending) ?
 157                 len + header_len : video->req_size;
 158
 159         /* Init the pending sgs with payload */
 160         sg = sg_next(sg);
 161
 162         for_each_sg(sg, iter, ureq->sgt.nents - 1, i) {
 163                 if (!len || !buf->sg || !buf->sg->length)
 164                         break;
 165
 166                 sg_left = buf->sg->length - buf->offset;
 167                 part = min_t(unsigned int, len, sg_left);
 168
 169                 sg_set_page(iter, sg_page(buf->sg), part, buf->offset);
 170
 171                 if (part == sg_left) {
 172                         buf->offset = 0;
 173                         buf->sg = sg_next(buf->sg);
 174                 } else {
 175                         buf->offset += part;
 176                 }
 177                 len -= part;
 178         }
 179
 180         /* Assign the video data with header. */
 181         req->buf = NULL;
 182         req->sg = ureq->sgt.sgl;
 183         req->num_sgs = i + 1;
 184
 185         req->length -= len;
 186         video->queue.buf_used += req->length - header_len;
 187
 188         if (buf->bytesused == video->queue.buf_used || !buf->sg ||
 189                         video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE) {
 190                 video->queue.buf_used = 0;
 191                 buf->state = UVC_BUF_STATE_DONE;
 192                 buf->offset = 0;
 193                 list_del(&buf->queue);
 194                 video->fid ^= UVC_STREAM_FID;
 195                 ureq->last_buf = buf;
 196         }
 197 }
 198
 199 static void
 200 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
 201                 struct uvc_buffer *buf)
 202 {
 203         void *mem = req->buf;
 204         struct uvc_request *ureq = req->context;
 205         int len = video->req_size;
 206         int ret;
 207
 208         /* Add the header. */
 209         ret = uvc_video_encode_header(video, buf, mem, len);
 210         mem += ret;
 211         len -= ret;
 212
 213         /* Process video data. */
 214         ret = uvc_video_encode_data(video, buf, mem, len);
 215         len -= ret;
 216
 217         req->length = video->req_size - len;
 218
 219         if (buf->bytesused == video->queue.buf_used ||
 220                         video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE) {
 221                 video->queue.buf_used = 0;
 222                 buf->state = UVC_BUF_STATE_DONE;
 223                 list_del(&buf->queue);
 224                 video->fid ^= UVC_STREAM_FID;
 225                 ureq->last_buf = buf;
 226         }
 227 }
 228
 229 /* --------------------------------------------------------------------------
 230  * Request handling
 231  */
 232
 233 /*
 234  * Callers must take care to hold req_lock when this function may be called
 235  * from multiple threads. For example, when frames are streaming to the host.
 236  */
 237 static void
 238 uvc_video_free_request(struct uvc_request *ureq, struct usb_ep *ep)
 239 {
 240         sg_free_table(&ureq->sgt);
 241         if (ureq->req && ep) {
 242                 usb_ep_free_request(ep, ureq->req);
 243                 ureq->req = NULL;
 244         }
 245
 246         kfree(ureq->req_buffer);
 247         ureq->req_buffer = NULL;
 248
 249         if (!list_empty(&ureq->list))
 250                 list_del_init(&ureq->list);
 251
 252         kfree(ureq);
 253 }
 254
 255 static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req)
 256 {
 257         int ret;
 258
 259         ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
 260         if (ret < 0) {
 261                 uvcg_err(&video->uvc->func, "Failed to queue request (%d).\n",
 262                          ret);
 263
 264                 /* If the endpoint is disabled the descriptor may be NULL. */
 265                 if (video->ep->desc) {
 266                         /* Isochronous endpoints can't be halted. */
 267                         if (usb_endpoint_xfer_bulk(video->ep->desc))
 268                                 usb_ep_set_halt(video->ep);
 269                 }
 270         }
 271
 272         return ret;
 273 }
 274
 275 /* This function must be called with video->req_lock held. */
 276 static int uvcg_video_usb_req_queue(struct uvc_video *video,
 277         struct usb_request *req, bool queue_to_ep)
 278 {
 279         bool is_bulk = video->max_payload_size;
 280         struct list_head *list = NULL;
 281
 282         if (!video->is_enabled)
 283                 return -ENODEV;
 284
 285         if (queue_to_ep) {
 286                 struct uvc_request *ureq = req->context;
 287                 /*
 288                  * With USB3 handling more requests at a higher speed, we can't
 289                  * afford to generate an interrupt for every request. Decide to
 290                  * interrupt:
 291                  *
 292                  * - When no more requests are available in the free queue, as
 293                  *   this may be our last chance to refill the endpoint's
 294                  *   request queue.
 295                  *
 296                  * - When this is request is the last request for the video
 297                  *   buffer, as we want to start sending the next video buffer
 298                  *   ASAP in case it doesn't get started already in the next
 299                  *   iteration of this loop.
 300                  *
 301                  * - Four times over the length of the requests queue (as
 302                  *   indicated by video->uvc_num_requests), as a trade-off
 303                  *   between latency and interrupt load.
 304                  */
 305                 if (list_empty(&video->req_free) || ureq->last_buf ||
 306                         !(video->req_int_count %
 307                         DIV_ROUND_UP(video->uvc_num_requests, 4))) {
 308                         video->req_int_count = 0;
 309                         req->no_interrupt = 0;
 310                 } else {
 311                         req->no_interrupt = 1;
 312                 }
 313                 video->req_int_count++;
 314                 return uvcg_video_ep_queue(video, req);
 315         }
 316         /*
 317          * If we're not queuing to the ep, for isoc we're queuing
 318          * to the req_ready list, otherwise req_free.
 319          */
 320         list = is_bulk ? &video->req_free : &video->req_ready;
 321         list_add_tail(&req->list, list);
 322         return 0;
 323 }
 324
 325 /*
 326  * Must only be called from uvcg_video_enable - since after that we only want to
 327  * queue requests to the endpoint from the uvc_video_complete complete handler.
 328  * This function is needed in order to 'kick start' the flow of requests from
 329  * gadget driver to the usb controller.
 330  */
 331 static void uvc_video_ep_queue_initial_requests(struct uvc_video *video)
 332 {
 333         struct usb_request *req = NULL;
 334         unsigned long flags = 0;
 335         unsigned int count = 0;
 336         int ret = 0;
 337
 338         /*
 339          * We only queue half of the free list since we still want to have
 340          * some free usb_requests in the free list for the video_pump async_wq
 341          * thread to encode uvc buffers into. Otherwise we could get into a
 342          * situation where the free list does not have any usb requests to
 343          * encode into - we always end up queueing 0 length requests to the
 344          * end point.
 345          */
 346         unsigned int half_list_size = video->uvc_num_requests / 2;
 347
 348         spin_lock_irqsave(&video->req_lock, flags);
 349         /*
 350          * Take these requests off the free list and queue them all to the
 351          * endpoint. Since we queue 0 length requests with the req_lock held,
 352          * there isn't any 'data' race involved here with the complete handler.
 353          */
 354         while (count < half_list_size) {
 355                 req = list_first_entry(&video->req_free, struct usb_request,
 356                                         list);
 357                 list_del(&req->list);
 358                 req->length = 0;
 359                 ret = uvcg_video_ep_queue(video, req);
 360                 if (ret < 0) {
 361                         uvcg_queue_cancel(&video->queue, 0);
 362                         break;
 363                 }
 364                 count++;
 365         }
 366         spin_unlock_irqrestore(&video->req_lock, flags);
 367 }
 368
 369 static void
 370 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 371 {
 372         struct uvc_request *ureq = req->context;
 373         struct uvc_video *video = ureq->video;
 374         struct uvc_video_queue *queue = &video->queue;
 375         struct uvc_buffer *last_buf;
 376         unsigned long flags;
 377         bool is_bulk = video->max_payload_size;
 378         int ret = 0;
 379
 380         spin_lock_irqsave(&video->req_lock, flags);
 381         if (!video->is_enabled) {
 382                 /*
 383                  * When is_enabled is false, uvcg_video_disable() ensures
 384                  * that in-flight uvc_buffers are returned, so we can
 385                  * safely call free_request without worrying about
 386                  * last_buf.
 387                  */
 388                 uvc_video_free_request(ureq, ep);
 389                 spin_unlock_irqrestore(&video->req_lock, flags);
 390                 return;
 391         }
 392
 393         last_buf = ureq->last_buf;
 394         ureq->last_buf = NULL;
 395         spin_unlock_irqrestore(&video->req_lock, flags);
 396
 397         switch (req->status) {
 398         case 0:
 399                 break;
 400
 401         case -EXDEV:
 402                 uvcg_dbg(&video->uvc->func, "VS request missed xfer.\n");
 403                 queue->flags |= UVC_QUEUE_DROP_INCOMPLETE;
 404                 break;
 405
 406         case -ESHUTDOWN:        /* disconnect from host. */
 407                 uvcg_dbg(&video->uvc->func, "VS request cancelled.\n");
 408                 uvcg_queue_cancel(queue, 1);
 409                 break;
 410
 411         default:
 412                 uvcg_warn(&video->uvc->func,
 413                           "VS request completed with status %d.\n",
 414                           req->status);
 415                 uvcg_queue_cancel(queue, 0);
 416         }
 417
 418         if (last_buf) {
 419                 spin_lock_irqsave(&queue->irqlock, flags);
 420                 uvcg_complete_buffer(queue, last_buf);
 421                 spin_unlock_irqrestore(&queue->irqlock, flags);
 422         }
 423
 424         spin_lock_irqsave(&video->req_lock, flags);
 425         /*
 426          * Video stream might have been disabled while we were
 427          * processing the current usb_request. So make sure
 428          * we're still streaming before queueing the usb_request
 429          * back to req_free
 430          */
 431         if (video->is_enabled) {
 432                 /*
 433                  * Here we check whether any request is available in the ready
 434                  * list. If it is, queue it to the ep and add the current
 435                  * usb_request to the req_free list - for video_pump to fill in.
 436                  * Otherwise, just use the current usb_request to queue a 0
 437                  * length request to the ep. Since we always add to the req_free
 438                  * list if we dequeue from the ready list, there will never
 439                  * be a situation where the req_free list is completely out of
 440                  * requests and cannot recover.
 441                  */
 442                 struct usb_request *to_queue = req;
 443
 444                 to_queue->length = 0;
 445                 if (!list_empty(&video->req_ready)) {
 446                         to_queue = list_first_entry(&video->req_ready,
 447                                 struct usb_request, list);
 448                         list_del(&to_queue->list);
 449                         list_add_tail(&req->list, &video->req_free);
 450                         /*
 451                          * Queue work to the wq as well since it is possible that a
 452                          * buffer may not have been completely encoded with the set of
 453                          * in-flight usb requests for whih the complete callbacks are
 454                          * firing.
 455                          * In that case, if we do not queue work to the worker thread,
 456                          * the buffer will never be marked as complete - and therefore
 457                          * not be returned to userpsace. As a result,
 458                          * dequeue -> queue -> dequeue flow of uvc buffers will not
 459                          * happen.
 460                          */
 461                         queue_work(video->async_wq, &video->pump);
 462                 }
 463                 /*
 464                  * Queue to the endpoint. The actual queueing to ep will
 465                  * only happen on one thread - the async_wq for bulk endpoints
 466                  * and this thread for isoc endpoints.
 467                  */
 468                 ret = uvcg_video_usb_req_queue(video, to_queue, !is_bulk);
 469                 if (ret < 0) {
 470                         /*
 471                          * Endpoint error, but the stream is still enabled.
 472                          * Put request back in req_free for it to be cleaned
 473                          * up later.
 474                          */
 475                         list_add_tail(&to_queue->list, &video->req_free);
 476                 }
 477         } else {
 478                 uvc_video_free_request(ureq, ep);
 479                 ret = 0;
 480         }
 481         spin_unlock_irqrestore(&video->req_lock, flags);
 482         if (ret < 0)
 483                 uvcg_queue_cancel(queue, 0);
 484 }
 485
 486 static int
 487 uvc_video_free_requests(struct uvc_video *video)
 488 {
 489         struct uvc_request *ureq, *temp;
 490
 491         list_for_each_entry_safe(ureq, temp, &video->ureqs, list)
 492                 uvc_video_free_request(ureq, video->ep);
 493
 494         INIT_LIST_HEAD(&video->ureqs);
 495         INIT_LIST_HEAD(&video->req_free);
 496         INIT_LIST_HEAD(&video->req_ready);
 497         video->req_size = 0;
 498         return 0;
 499 }
 500
 501 static int
 502 uvc_video_alloc_requests(struct uvc_video *video)
 503 {
 504         struct uvc_request *ureq;
 505         unsigned int req_size;
 506         unsigned int i;
 507         int ret = -ENOMEM;
 508
 509         BUG_ON(video->req_size);
 510
 511         req_size = video->ep->maxpacket
 512                  * max_t(unsigned int, video->ep->maxburst, 1)
 513                  * (video->ep->mult);
 514
 515         for (i = 0; i < video->uvc_num_requests; i++) {
 516                 ureq = kzalloc(sizeof(struct uvc_request), GFP_KERNEL);
 517                 if (ureq == NULL)
 518                         goto error;
 519
 520                 INIT_LIST_HEAD(&ureq->list);
 521
 522                 list_add_tail(&ureq->list, &video->ureqs);
 523
 524                 ureq->req_buffer = kmalloc(req_size, GFP_KERNEL);
 525                 if (ureq->req_buffer == NULL)
 526                         goto error;
 527
 528                 ureq->req = usb_ep_alloc_request(video->ep, GFP_KERNEL);
 529                 if (ureq->req == NULL)
 530                         goto error;
 531
 532                 ureq->req->buf = ureq->req_buffer;
 533                 ureq->req->length = 0;
 534                 ureq->req->complete = uvc_video_complete;
 535                 ureq->req->context = ureq;
 536                 ureq->video = video;
 537                 ureq->last_buf = NULL;
 538
 539                 list_add_tail(&ureq->req->list, &video->req_free);
 540                 /* req_size/PAGE_SIZE + 1 for overruns and + 1 for header */
 541                 sg_alloc_table(&ureq->sgt,
 542                                DIV_ROUND_UP(req_size - UVCG_REQUEST_HEADER_LEN,
 543                                             PAGE_SIZE) + 2, GFP_KERNEL);
 544         }
 545
 546         video->req_size = req_size;
 547
 548         return 0;
 549
 550 error:
 551         uvc_video_free_requests(video);
 552         return ret;
 553 }
 554
 555 /* --------------------------------------------------------------------------
 556  * Video streaming
 557  */
 558
 559 /*
 560  * uvcg_video_pump - Pump video data into the USB requests
 561  *
 562  * This function fills the available USB requests (listed in req_free) with
 563  * video data from the queued buffers.
 564  */
 565 static void uvcg_video_pump(struct work_struct *work)
 566 {
 567         struct uvc_video *video = container_of(work, struct uvc_video, pump);
 568         struct uvc_video_queue *queue = &video->queue;
 569         /* video->max_payload_size is only set when using bulk transfer */
 570         bool is_bulk = video->max_payload_size;
 571         struct usb_request *req = NULL;
 572         struct uvc_buffer *buf;
 573         unsigned long flags;
 574         int ret = 0;
 575
 576         while (true) {
 577                 if (!video->ep->enabled)
 578                         return;
 579
 580                 /*
 581                  * Check is_enabled and retrieve the first available USB
 582                  * request, protected by the request lock.
 583                  */
 584                 spin_lock_irqsave(&video->req_lock, flags);
 585                 if (!video->is_enabled || list_empty(&video->req_free)) {
 586                         spin_unlock_irqrestore(&video->req_lock, flags);
 587                         return;
 588                 }
 589                 req = list_first_entry(&video->req_free, struct usb_request,
 590                                         list);
 591                 list_del(&req->list);
 592                 spin_unlock_irqrestore(&video->req_lock, flags);
 593
 594                 /*
 595                  * Retrieve the first available video buffer and fill the
 596                  * request, protected by the video queue irqlock.
 597                  */
 598                 spin_lock_irqsave(&queue->irqlock, flags);
 599                 buf = uvcg_queue_head(queue);
 600                 if (!buf) {
 601                         /*
 602                          * Either the queue has been disconnected or no video buffer
 603                          * available for bulk transfer. Either way, stop processing
 604                          * further.
 605                          */
 606                         spin_unlock_irqrestore(&queue->irqlock, flags);
 607                         break;
 608                 }
 609
 610                 video->encode(req, video, buf);
 611
 612                 spin_unlock_irqrestore(&queue->irqlock, flags);
 613
 614                 spin_lock_irqsave(&video->req_lock, flags);
 615                 /* For bulk end points we queue from the worker thread
 616                  * since we would preferably not want to wait on requests
 617                  * to be ready, in the uvcg_video_complete() handler.
 618                  * For isoc endpoints we add the request to the ready list
 619                  * and only queue it to the endpoint from the complete handler.
 620                  */
 621                 ret = uvcg_video_usb_req_queue(video, req, is_bulk);
 622                 spin_unlock_irqrestore(&video->req_lock, flags);
 623
 624                 if (ret < 0) {
 625                         uvcg_queue_cancel(queue, 0);
 626                         break;
 627                 }
 628
 629                 /* The request is owned by  the endpoint / ready list. */
 630                 req = NULL;
 631         }
 632
 633         if (!req)
 634                 return;
 635
 636         spin_lock_irqsave(&video->req_lock, flags);
 637         if (video->is_enabled)
 638                 list_add_tail(&req->list, &video->req_free);
 639         else
 640                 uvc_video_free_request(req->context, video->ep);
 641         spin_unlock_irqrestore(&video->req_lock, flags);
 642 }
 643
 644 /*
 645  * Disable the video stream
 646  */
 647 int
 648 uvcg_video_disable(struct uvc_video *video)
 649 {
 650         unsigned long flags;
 651         struct list_head inflight_bufs;
 652         struct usb_request *req, *temp;
 653         struct uvc_buffer *buf, *btemp;
 654         struct uvc_request *ureq, *utemp;
 655
 656         if (video->ep == NULL) {
 657                 uvcg_info(&video->uvc->func,
 658                           "Video disable failed, device is uninitialized.\n");
 659                 return -ENODEV;
 660         }
 661
 662         INIT_LIST_HEAD(&inflight_bufs);
 663         spin_lock_irqsave(&video->req_lock, flags);
 664         video->is_enabled = false;
 665
 666         /*
 667          * Remove any in-flight buffers from the uvc_requests
 668          * because we want to return them before cancelling the
 669          * queue. This ensures that we aren't stuck waiting for
 670          * all complete callbacks to come through before disabling
 671          * vb2 queue.
 672          */
 673         list_for_each_entry(ureq, &video->ureqs, list) {
 674                 if (ureq->last_buf) {
 675                         list_add_tail(&ureq->last_buf->queue, &inflight_bufs);
 676                         ureq->last_buf = NULL;
 677                 }
 678         }
 679         spin_unlock_irqrestore(&video->req_lock, flags);
 680
 681         cancel_work_sync(&video->pump);
 682         uvcg_queue_cancel(&video->queue, 0);
 683
 684         spin_lock_irqsave(&video->req_lock, flags);
 685         /*
 686          * Remove all uvc_requests from ureqs with list_del_init
 687          * This lets uvc_video_free_request correctly identify
 688          * if the uvc_request is attached to a list or not when freeing
 689          * memory.
 690          */
 691         list_for_each_entry_safe(ureq, utemp, &video->ureqs, list)
 692                 list_del_init(&ureq->list);
 693
 694         list_for_each_entry_safe(req, temp, &video->req_free, list) {
 695                 list_del(&req->list);
 696                 uvc_video_free_request(req->context, video->ep);
 697         }
 698
 699         list_for_each_entry_safe(req, temp, &video->req_ready, list) {
 700                 list_del(&req->list);
 701                 uvc_video_free_request(req->context, video->ep);
 702         }
 703
 704         INIT_LIST_HEAD(&video->ureqs);
 705         INIT_LIST_HEAD(&video->req_free);
 706         INIT_LIST_HEAD(&video->req_ready);
 707         video->req_size = 0;
 708         spin_unlock_irqrestore(&video->req_lock, flags);
 709
 710         /*
 711          * Return all the video buffers before disabling the queue.
 712          */
 713         spin_lock_irqsave(&video->queue.irqlock, flags);
 714         list_for_each_entry_safe(buf, btemp, &inflight_bufs, queue) {
 715                 list_del(&buf->queue);
 716                 uvcg_complete_buffer(&video->queue, buf);
 717         }
 718         spin_unlock_irqrestore(&video->queue.irqlock, flags);
 719
 720         uvcg_queue_enable(&video->queue, 0);
 721         return 0;
 722 }
 723
 724 /*
 725  * Enable the video stream.
 726  */
 727 int uvcg_video_enable(struct uvc_video *video)
 728 {
 729         int ret;
 730
 731         if (video->ep == NULL) {
 732                 uvcg_info(&video->uvc->func,
 733                           "Video enable failed, device is uninitialized.\n");
 734                 return -ENODEV;
 735         }
 736
 737         /*
 738          * Safe to access request related fields without req_lock because
 739          * this is the only thread currently active, and no other
 740          * request handling thread will become active until this function
 741          * returns.
 742          */
 743         video->is_enabled = true;
 744
 745         if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
 746                 return ret;
 747
 748         if ((ret = uvc_video_alloc_requests(video)) < 0)
 749                 return ret;
 750
 751         if (video->max_payload_size) {
 752                 video->encode = uvc_video_encode_bulk;
 753                 video->payload_size = 0;
 754         } else
 755                 video->encode = video->queue.use_sg ?
 756                         uvc_video_encode_isoc_sg : uvc_video_encode_isoc;
 757
 758         video->req_int_count = 0;
 759
 760         uvc_video_ep_queue_initial_requests(video);
 761
 762         return ret;
 763 }
 764
 765 /*
 766  * Initialize the UVC video stream.
 767  */
 768 int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc)
 769 {
 770         video->is_enabled = false;
 771         INIT_LIST_HEAD(&video->ureqs);
 772         INIT_LIST_HEAD(&video->req_free);
 773         INIT_LIST_HEAD(&video->req_ready);
 774         spin_lock_init(&video->req_lock);
 775         INIT_WORK(&video->pump, uvcg_video_pump);
 776
 777         /* Allocate a work queue for asynchronous video pump handler. */
 778         video->async_wq = alloc_workqueue("uvcgadget", WQ_UNBOUND | WQ_HIGHPRI, 0);
 779         if (!video->async_wq)
 780                 return -EINVAL;
 781
 782         video->uvc = uvc;
 783         video->fcc = V4L2_PIX_FMT_YUYV;
 784         video->bpp = 16;
 785         video->width = 320;
 786         video->height = 240;
 787         video->imagesize = 320 * 240 * 2;
 788
 789         /* Initialize the video buffers queue. */
 790         uvcg_queue_init(&video->queue, uvc->v4l2_dev.dev->parent,
 791                         V4L2_BUF_TYPE_VIDEO_OUTPUT, &video->mutex);
 792         return 0;
 793 }