Commit | Line | Data |
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cdda479f LP |
1 | /* |
2 | * uvc_queue.c -- USB Video Class driver - Buffers management | |
3 | * | |
4 | * Copyright (C) 2005-2010 | |
5 | * Laurent Pinchart (laurent.pinchart@ideasonboard.com) | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
cdda479f LP |
11 | */ |
12 | ||
13 | #include <linux/kernel.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/list.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/usb.h> | |
18 | #include <linux/videodev2.h> | |
19 | #include <linux/vmalloc.h> | |
20 | #include <linux/wait.h> | |
60063497 | 21 | #include <linux/atomic.h> |
cdda479f LP |
22 | |
23 | #include "uvc.h" | |
24 | ||
25 | /* ------------------------------------------------------------------------ | |
26 | * Video buffers queue management. | |
27 | * | |
28 | * Video queues is initialized by uvc_queue_init(). The function performs | |
29 | * basic initialization of the uvc_video_queue struct and never fails. | |
30 | * | |
31 | * Video buffer allocation and freeing are performed by uvc_alloc_buffers and | |
32 | * uvc_free_buffers respectively. The former acquires the video queue lock, | |
33 | * while the later must be called with the lock held (so that allocation can | |
34 | * free previously allocated buffers). Trying to free buffers that are mapped | |
35 | * to user space will return -EBUSY. | |
36 | * | |
37 | * Video buffers are managed using two queues. However, unlike most USB video | |
38 | * drivers that use an in queue and an out queue, we use a main queue to hold | |
39 | * all queued buffers (both 'empty' and 'done' buffers), and an irq queue to | |
40 | * hold empty buffers. This design (copied from video-buf) minimizes locking | |
41 | * in interrupt, as only one queue is shared between interrupt and user | |
42 | * contexts. | |
43 | * | |
44 | * Use cases | |
45 | * --------- | |
46 | * | |
47 | * Unless stated otherwise, all operations that modify the irq buffers queue | |
48 | * are protected by the irq spinlock. | |
49 | * | |
50 | * 1. The user queues the buffers, starts streaming and dequeues a buffer. | |
51 | * | |
52 | * The buffers are added to the main and irq queues. Both operations are | |
53 | * protected by the queue lock, and the later is protected by the irq | |
54 | * spinlock as well. | |
55 | * | |
56 | * The completion handler fetches a buffer from the irq queue and fills it | |
57 | * with video data. If no buffer is available (irq queue empty), the handler | |
58 | * returns immediately. | |
59 | * | |
60 | * When the buffer is full, the completion handler removes it from the irq | |
61 | * queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait queue. | |
62 | * At that point, any process waiting on the buffer will be woken up. If a | |
63 | * process tries to dequeue a buffer after it has been marked ready, the | |
64 | * dequeing will succeed immediately. | |
65 | * | |
66 | * 2. Buffers are queued, user is waiting on a buffer and the device gets | |
67 | * disconnected. | |
68 | * | |
69 | * When the device is disconnected, the kernel calls the completion handler | |
70 | * with an appropriate status code. The handler marks all buffers in the | |
71 | * irq queue as being erroneous (UVC_BUF_STATE_ERROR) and wakes them up so | |
72 | * that any process waiting on a buffer gets woken up. | |
73 | * | |
74 | * Waking up up the first buffer on the irq list is not enough, as the | |
75 | * process waiting on the buffer might restart the dequeue operation | |
76 | * immediately. | |
77 | * | |
78 | */ | |
79 | ||
5d9955f8 LP |
80 | static void |
81 | uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type) | |
cdda479f LP |
82 | { |
83 | mutex_init(&queue->mutex); | |
84 | spin_lock_init(&queue->irqlock); | |
85 | INIT_LIST_HEAD(&queue->mainqueue); | |
86 | INIT_LIST_HEAD(&queue->irqqueue); | |
87 | queue->type = type; | |
88 | } | |
89 | ||
5d9955f8 LP |
90 | /* |
91 | * Free the video buffers. | |
92 | * | |
93 | * This function must be called with the queue lock held. | |
94 | */ | |
95 | static int uvc_free_buffers(struct uvc_video_queue *queue) | |
96 | { | |
97 | unsigned int i; | |
98 | ||
99 | for (i = 0; i < queue->count; ++i) { | |
100 | if (queue->buffer[i].vma_use_count != 0) | |
101 | return -EBUSY; | |
102 | } | |
103 | ||
104 | if (queue->count) { | |
105 | vfree(queue->mem); | |
106 | queue->count = 0; | |
107 | } | |
108 | ||
109 | return 0; | |
110 | } | |
111 | ||
cdda479f LP |
112 | /* |
113 | * Allocate the video buffers. | |
114 | * | |
115 | * Pages are reserved to make sure they will not be swapped, as they will be | |
116 | * filled in the URB completion handler. | |
117 | * | |
118 | * Buffers will be individually mapped, so they must all be page aligned. | |
119 | */ | |
5d9955f8 LP |
120 | static int |
121 | uvc_alloc_buffers(struct uvc_video_queue *queue, unsigned int nbuffers, | |
122 | unsigned int buflength) | |
cdda479f LP |
123 | { |
124 | unsigned int bufsize = PAGE_ALIGN(buflength); | |
125 | unsigned int i; | |
126 | void *mem = NULL; | |
127 | int ret; | |
128 | ||
129 | if (nbuffers > UVC_MAX_VIDEO_BUFFERS) | |
130 | nbuffers = UVC_MAX_VIDEO_BUFFERS; | |
131 | ||
132 | mutex_lock(&queue->mutex); | |
133 | ||
134 | if ((ret = uvc_free_buffers(queue)) < 0) | |
135 | goto done; | |
136 | ||
137 | /* Bail out if no buffers should be allocated. */ | |
138 | if (nbuffers == 0) | |
139 | goto done; | |
140 | ||
141 | /* Decrement the number of buffers until allocation succeeds. */ | |
142 | for (; nbuffers > 0; --nbuffers) { | |
143 | mem = vmalloc_32(nbuffers * bufsize); | |
144 | if (mem != NULL) | |
145 | break; | |
146 | } | |
147 | ||
148 | if (mem == NULL) { | |
149 | ret = -ENOMEM; | |
150 | goto done; | |
151 | } | |
152 | ||
153 | for (i = 0; i < nbuffers; ++i) { | |
154 | memset(&queue->buffer[i], 0, sizeof queue->buffer[i]); | |
155 | queue->buffer[i].buf.index = i; | |
156 | queue->buffer[i].buf.m.offset = i * bufsize; | |
157 | queue->buffer[i].buf.length = buflength; | |
158 | queue->buffer[i].buf.type = queue->type; | |
159 | queue->buffer[i].buf.sequence = 0; | |
160 | queue->buffer[i].buf.field = V4L2_FIELD_NONE; | |
161 | queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP; | |
162 | queue->buffer[i].buf.flags = 0; | |
163 | init_waitqueue_head(&queue->buffer[i].wait); | |
164 | } | |
165 | ||
166 | queue->mem = mem; | |
167 | queue->count = nbuffers; | |
168 | queue->buf_size = bufsize; | |
169 | ret = nbuffers; | |
170 | ||
171 | done: | |
172 | mutex_unlock(&queue->mutex); | |
173 | return ret; | |
174 | } | |
175 | ||
cdda479f LP |
176 | static void __uvc_query_buffer(struct uvc_buffer *buf, |
177 | struct v4l2_buffer *v4l2_buf) | |
178 | { | |
179 | memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf); | |
180 | ||
181 | if (buf->vma_use_count) | |
182 | v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED; | |
183 | ||
184 | switch (buf->state) { | |
185 | case UVC_BUF_STATE_ERROR: | |
186 | case UVC_BUF_STATE_DONE: | |
187 | v4l2_buf->flags |= V4L2_BUF_FLAG_DONE; | |
188 | break; | |
189 | case UVC_BUF_STATE_QUEUED: | |
190 | case UVC_BUF_STATE_ACTIVE: | |
191 | v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED; | |
192 | break; | |
193 | case UVC_BUF_STATE_IDLE: | |
194 | default: | |
195 | break; | |
196 | } | |
197 | } | |
198 | ||
5d9955f8 LP |
199 | static int |
200 | uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf) | |
cdda479f LP |
201 | { |
202 | int ret = 0; | |
203 | ||
204 | mutex_lock(&queue->mutex); | |
205 | if (v4l2_buf->index >= queue->count) { | |
206 | ret = -EINVAL; | |
207 | goto done; | |
208 | } | |
209 | ||
210 | __uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf); | |
211 | ||
212 | done: | |
213 | mutex_unlock(&queue->mutex); | |
214 | return ret; | |
215 | } | |
216 | ||
217 | /* | |
218 | * Queue a video buffer. Attempting to queue a buffer that has already been | |
219 | * queued will return -EINVAL. | |
220 | */ | |
5d9955f8 LP |
221 | static int |
222 | uvc_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf) | |
cdda479f LP |
223 | { |
224 | struct uvc_buffer *buf; | |
225 | unsigned long flags; | |
226 | int ret = 0; | |
227 | ||
228 | uvc_trace(UVC_TRACE_CAPTURE, "Queuing buffer %u.\n", v4l2_buf->index); | |
229 | ||
230 | if (v4l2_buf->type != queue->type || | |
231 | v4l2_buf->memory != V4L2_MEMORY_MMAP) { | |
232 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) " | |
233 | "and/or memory (%u).\n", v4l2_buf->type, | |
234 | v4l2_buf->memory); | |
235 | return -EINVAL; | |
236 | } | |
237 | ||
238 | mutex_lock(&queue->mutex); | |
239 | if (v4l2_buf->index >= queue->count) { | |
240 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n"); | |
241 | ret = -EINVAL; | |
242 | goto done; | |
243 | } | |
244 | ||
245 | buf = &queue->buffer[v4l2_buf->index]; | |
246 | if (buf->state != UVC_BUF_STATE_IDLE) { | |
247 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state " | |
248 | "(%u).\n", buf->state); | |
249 | ret = -EINVAL; | |
250 | goto done; | |
251 | } | |
252 | ||
253 | if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT && | |
254 | v4l2_buf->bytesused > buf->buf.length) { | |
255 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n"); | |
256 | ret = -EINVAL; | |
257 | goto done; | |
258 | } | |
259 | ||
260 | if (v4l2_buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) | |
261 | buf->buf.bytesused = 0; | |
262 | else | |
263 | buf->buf.bytesused = v4l2_buf->bytesused; | |
264 | ||
265 | spin_lock_irqsave(&queue->irqlock, flags); | |
266 | if (queue->flags & UVC_QUEUE_DISCONNECTED) { | |
267 | spin_unlock_irqrestore(&queue->irqlock, flags); | |
268 | ret = -ENODEV; | |
269 | goto done; | |
270 | } | |
271 | buf->state = UVC_BUF_STATE_QUEUED; | |
272 | ||
273 | ret = (queue->flags & UVC_QUEUE_PAUSED) != 0; | |
274 | queue->flags &= ~UVC_QUEUE_PAUSED; | |
275 | ||
276 | list_add_tail(&buf->stream, &queue->mainqueue); | |
277 | list_add_tail(&buf->queue, &queue->irqqueue); | |
278 | spin_unlock_irqrestore(&queue->irqlock, flags); | |
279 | ||
280 | done: | |
281 | mutex_unlock(&queue->mutex); | |
282 | return ret; | |
283 | } | |
284 | ||
285 | static int uvc_queue_waiton(struct uvc_buffer *buf, int nonblocking) | |
286 | { | |
287 | if (nonblocking) { | |
288 | return (buf->state != UVC_BUF_STATE_QUEUED && | |
289 | buf->state != UVC_BUF_STATE_ACTIVE) | |
290 | ? 0 : -EAGAIN; | |
291 | } | |
292 | ||
293 | return wait_event_interruptible(buf->wait, | |
294 | buf->state != UVC_BUF_STATE_QUEUED && | |
295 | buf->state != UVC_BUF_STATE_ACTIVE); | |
296 | } | |
297 | ||
298 | /* | |
299 | * Dequeue a video buffer. If nonblocking is false, block until a buffer is | |
300 | * available. | |
301 | */ | |
5d9955f8 LP |
302 | static int |
303 | uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *v4l2_buf, | |
304 | int nonblocking) | |
cdda479f LP |
305 | { |
306 | struct uvc_buffer *buf; | |
307 | int ret = 0; | |
308 | ||
309 | if (v4l2_buf->type != queue->type || | |
310 | v4l2_buf->memory != V4L2_MEMORY_MMAP) { | |
311 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer type (%u) " | |
312 | "and/or memory (%u).\n", v4l2_buf->type, | |
313 | v4l2_buf->memory); | |
314 | return -EINVAL; | |
315 | } | |
316 | ||
317 | mutex_lock(&queue->mutex); | |
318 | if (list_empty(&queue->mainqueue)) { | |
319 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Empty buffer queue.\n"); | |
320 | ret = -EINVAL; | |
321 | goto done; | |
322 | } | |
323 | ||
324 | buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream); | |
325 | if ((ret = uvc_queue_waiton(buf, nonblocking)) < 0) | |
326 | goto done; | |
327 | ||
328 | uvc_trace(UVC_TRACE_CAPTURE, "Dequeuing buffer %u (%u, %u bytes).\n", | |
329 | buf->buf.index, buf->state, buf->buf.bytesused); | |
330 | ||
331 | switch (buf->state) { | |
332 | case UVC_BUF_STATE_ERROR: | |
333 | uvc_trace(UVC_TRACE_CAPTURE, "[W] Corrupted data " | |
334 | "(transmission error).\n"); | |
335 | ret = -EIO; | |
336 | case UVC_BUF_STATE_DONE: | |
337 | buf->state = UVC_BUF_STATE_IDLE; | |
338 | break; | |
339 | ||
340 | case UVC_BUF_STATE_IDLE: | |
341 | case UVC_BUF_STATE_QUEUED: | |
342 | case UVC_BUF_STATE_ACTIVE: | |
343 | default: | |
344 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Invalid buffer state %u " | |
345 | "(driver bug?).\n", buf->state); | |
346 | ret = -EINVAL; | |
347 | goto done; | |
348 | } | |
349 | ||
350 | list_del(&buf->stream); | |
351 | __uvc_query_buffer(buf, v4l2_buf); | |
352 | ||
353 | done: | |
354 | mutex_unlock(&queue->mutex); | |
355 | return ret; | |
356 | } | |
357 | ||
358 | /* | |
359 | * Poll the video queue. | |
360 | * | |
361 | * This function implements video queue polling and is intended to be used by | |
362 | * the device poll handler. | |
363 | */ | |
5d9955f8 LP |
364 | static unsigned int |
365 | uvc_queue_poll(struct uvc_video_queue *queue, struct file *file, | |
366 | poll_table *wait) | |
cdda479f LP |
367 | { |
368 | struct uvc_buffer *buf; | |
369 | unsigned int mask = 0; | |
370 | ||
371 | mutex_lock(&queue->mutex); | |
372 | if (list_empty(&queue->mainqueue)) | |
373 | goto done; | |
374 | ||
375 | buf = list_first_entry(&queue->mainqueue, struct uvc_buffer, stream); | |
376 | ||
377 | poll_wait(file, &buf->wait, wait); | |
378 | if (buf->state == UVC_BUF_STATE_DONE || | |
379 | buf->state == UVC_BUF_STATE_ERROR) | |
380 | mask |= POLLOUT | POLLWRNORM; | |
381 | ||
382 | done: | |
383 | mutex_unlock(&queue->mutex); | |
384 | return mask; | |
385 | } | |
386 | ||
387 | /* | |
388 | * VMA operations. | |
389 | */ | |
390 | static void uvc_vm_open(struct vm_area_struct *vma) | |
391 | { | |
392 | struct uvc_buffer *buffer = vma->vm_private_data; | |
393 | buffer->vma_use_count++; | |
394 | } | |
395 | ||
396 | static void uvc_vm_close(struct vm_area_struct *vma) | |
397 | { | |
398 | struct uvc_buffer *buffer = vma->vm_private_data; | |
399 | buffer->vma_use_count--; | |
400 | } | |
401 | ||
402 | static struct vm_operations_struct uvc_vm_ops = { | |
403 | .open = uvc_vm_open, | |
404 | .close = uvc_vm_close, | |
405 | }; | |
406 | ||
407 | /* | |
408 | * Memory-map a buffer. | |
409 | * | |
410 | * This function implements video buffer memory mapping and is intended to be | |
411 | * used by the device mmap handler. | |
412 | */ | |
5d9955f8 LP |
413 | static int |
414 | uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma) | |
cdda479f LP |
415 | { |
416 | struct uvc_buffer *uninitialized_var(buffer); | |
417 | struct page *page; | |
418 | unsigned long addr, start, size; | |
419 | unsigned int i; | |
420 | int ret = 0; | |
421 | ||
422 | start = vma->vm_start; | |
423 | size = vma->vm_end - vma->vm_start; | |
424 | ||
425 | mutex_lock(&queue->mutex); | |
426 | ||
427 | for (i = 0; i < queue->count; ++i) { | |
428 | buffer = &queue->buffer[i]; | |
429 | if ((buffer->buf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff) | |
430 | break; | |
431 | } | |
432 | ||
433 | if (i == queue->count || size != queue->buf_size) { | |
434 | ret = -EINVAL; | |
435 | goto done; | |
436 | } | |
437 | ||
438 | /* | |
439 | * VM_IO marks the area as being an mmaped region for I/O to a | |
440 | * device. It also prevents the region from being core dumped. | |
441 | */ | |
442 | vma->vm_flags |= VM_IO; | |
443 | ||
444 | addr = (unsigned long)queue->mem + buffer->buf.m.offset; | |
445 | while (size > 0) { | |
446 | page = vmalloc_to_page((void *)addr); | |
447 | if ((ret = vm_insert_page(vma, start, page)) < 0) | |
448 | goto done; | |
449 | ||
450 | start += PAGE_SIZE; | |
451 | addr += PAGE_SIZE; | |
452 | size -= PAGE_SIZE; | |
453 | } | |
454 | ||
455 | vma->vm_ops = &uvc_vm_ops; | |
456 | vma->vm_private_data = buffer; | |
457 | uvc_vm_open(vma); | |
458 | ||
459 | done: | |
460 | mutex_unlock(&queue->mutex); | |
461 | return ret; | |
462 | } | |
463 | ||
5d9955f8 LP |
464 | /* |
465 | * Cancel the video buffers queue. | |
466 | * | |
467 | * Cancelling the queue marks all buffers on the irq queue as erroneous, | |
468 | * wakes them up and removes them from the queue. | |
469 | * | |
470 | * If the disconnect parameter is set, further calls to uvc_queue_buffer will | |
471 | * fail with -ENODEV. | |
472 | * | |
473 | * This function acquires the irq spinlock and can be called from interrupt | |
474 | * context. | |
475 | */ | |
476 | static void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect) | |
477 | { | |
478 | struct uvc_buffer *buf; | |
479 | unsigned long flags; | |
480 | ||
481 | spin_lock_irqsave(&queue->irqlock, flags); | |
482 | while (!list_empty(&queue->irqqueue)) { | |
483 | buf = list_first_entry(&queue->irqqueue, struct uvc_buffer, | |
484 | queue); | |
485 | list_del(&buf->queue); | |
486 | buf->state = UVC_BUF_STATE_ERROR; | |
487 | wake_up(&buf->wait); | |
488 | } | |
489 | /* This must be protected by the irqlock spinlock to avoid race | |
490 | * conditions between uvc_queue_buffer and the disconnection event that | |
491 | * could result in an interruptible wait in uvc_dequeue_buffer. Do not | |
492 | * blindly replace this logic by checking for the UVC_DEV_DISCONNECTED | |
493 | * state outside the queue code. | |
494 | */ | |
495 | if (disconnect) | |
496 | queue->flags |= UVC_QUEUE_DISCONNECTED; | |
497 | spin_unlock_irqrestore(&queue->irqlock, flags); | |
498 | } | |
499 | ||
cdda479f LP |
500 | /* |
501 | * Enable or disable the video buffers queue. | |
502 | * | |
503 | * The queue must be enabled before starting video acquisition and must be | |
504 | * disabled after stopping it. This ensures that the video buffers queue | |
505 | * state can be properly initialized before buffers are accessed from the | |
506 | * interrupt handler. | |
507 | * | |
508 | * Enabling the video queue initializes parameters (such as sequence number, | |
509 | * sync pattern, ...). If the queue is already enabled, return -EBUSY. | |
510 | * | |
511 | * Disabling the video queue cancels the queue and removes all buffers from | |
512 | * the main queue. | |
513 | * | |
514 | * This function can't be called from interrupt context. Use | |
515 | * uvc_queue_cancel() instead. | |
516 | */ | |
5d9955f8 | 517 | static int uvc_queue_enable(struct uvc_video_queue *queue, int enable) |
cdda479f LP |
518 | { |
519 | unsigned int i; | |
520 | int ret = 0; | |
521 | ||
522 | mutex_lock(&queue->mutex); | |
523 | if (enable) { | |
524 | if (uvc_queue_streaming(queue)) { | |
525 | ret = -EBUSY; | |
526 | goto done; | |
527 | } | |
528 | queue->sequence = 0; | |
529 | queue->flags |= UVC_QUEUE_STREAMING; | |
530 | queue->buf_used = 0; | |
531 | } else { | |
532 | uvc_queue_cancel(queue, 0); | |
533 | INIT_LIST_HEAD(&queue->mainqueue); | |
534 | ||
535 | for (i = 0; i < queue->count; ++i) | |
536 | queue->buffer[i].state = UVC_BUF_STATE_IDLE; | |
537 | ||
538 | queue->flags &= ~UVC_QUEUE_STREAMING; | |
539 | } | |
540 | ||
541 | done: | |
542 | mutex_unlock(&queue->mutex); | |
543 | return ret; | |
544 | } | |
545 | ||
5d9955f8 LP |
546 | static struct uvc_buffer * |
547 | uvc_queue_next_buffer(struct uvc_video_queue *queue, struct uvc_buffer *buf) | |
cdda479f LP |
548 | { |
549 | struct uvc_buffer *nextbuf; | |
550 | unsigned long flags; | |
551 | ||
552 | if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) && | |
553 | buf->buf.length != buf->buf.bytesused) { | |
554 | buf->state = UVC_BUF_STATE_QUEUED; | |
555 | buf->buf.bytesused = 0; | |
556 | return buf; | |
557 | } | |
558 | ||
559 | spin_lock_irqsave(&queue->irqlock, flags); | |
560 | list_del(&buf->queue); | |
561 | if (!list_empty(&queue->irqqueue)) | |
562 | nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer, | |
563 | queue); | |
564 | else | |
565 | nextbuf = NULL; | |
566 | spin_unlock_irqrestore(&queue->irqlock, flags); | |
567 | ||
568 | buf->buf.sequence = queue->sequence++; | |
569 | do_gettimeofday(&buf->buf.timestamp); | |
570 | ||
571 | wake_up(&buf->wait); | |
572 | return nextbuf; | |
573 | } | |
574 | ||
5d9955f8 | 575 | static struct uvc_buffer *uvc_queue_head(struct uvc_video_queue *queue) |
cdda479f LP |
576 | { |
577 | struct uvc_buffer *buf = NULL; | |
578 | ||
579 | if (!list_empty(&queue->irqqueue)) | |
580 | buf = list_first_entry(&queue->irqqueue, struct uvc_buffer, | |
581 | queue); | |
582 | else | |
583 | queue->flags |= UVC_QUEUE_PAUSED; | |
584 | ||
585 | return buf; | |
586 | } | |
587 |