diff options
Diffstat (limited to 'drivers/media/video/uvc/uvc_queue.c')
-rw-r--r-- | drivers/media/video/uvc/uvc_queue.c | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/drivers/media/video/uvc/uvc_queue.c b/drivers/media/video/uvc/uvc_queue.c index 42546342e97d..0155752e4a5a 100644 --- a/drivers/media/video/uvc/uvc_queue.c +++ b/drivers/media/video/uvc/uvc_queue.c | |||
@@ -1,7 +1,7 @@ | |||
1 | /* | 1 | /* |
2 | * uvc_queue.c -- USB Video Class driver - Buffers management | 2 | * uvc_queue.c -- USB Video Class driver - Buffers management |
3 | * | 3 | * |
4 | * Copyright (C) 2005-2008 | 4 | * Copyright (C) 2005-2009 |
5 | * Laurent Pinchart (laurent.pinchart@skynet.be) | 5 | * Laurent Pinchart (laurent.pinchart@skynet.be) |
6 | * | 6 | * |
7 | * This program is free software; you can redistribute it and/or modify | 7 | * This program is free software; you can redistribute it and/or modify |
@@ -12,7 +12,6 @@ | |||
12 | */ | 12 | */ |
13 | 13 | ||
14 | #include <linux/kernel.h> | 14 | #include <linux/kernel.h> |
15 | #include <linux/version.h> | ||
16 | #include <linux/mm.h> | 15 | #include <linux/mm.h> |
17 | #include <linux/list.h> | 16 | #include <linux/list.h> |
18 | #include <linux/module.h> | 17 | #include <linux/module.h> |
@@ -37,22 +36,22 @@ | |||
37 | * to user space will return -EBUSY. | 36 | * to user space will return -EBUSY. |
38 | * | 37 | * |
39 | * Video buffers are managed using two queues. However, unlike most USB video | 38 | * Video buffers are managed using two queues. However, unlike most USB video |
40 | * drivers which use an in queue and an out queue, we use a main queue which | 39 | * drivers that use an in queue and an out queue, we use a main queue to hold |
41 | * holds all queued buffers (both 'empty' and 'done' buffers), and an irq | 40 | * all queued buffers (both 'empty' and 'done' buffers), and an irq queue to |
42 | * queue which holds empty buffers. This design (copied from video-buf) | 41 | * hold empty buffers. This design (copied from video-buf) minimizes locking |
43 | * minimizes locking in interrupt, as only one queue is shared between | 42 | * in interrupt, as only one queue is shared between interrupt and user |
44 | * interrupt and user contexts. | 43 | * contexts. |
45 | * | 44 | * |
46 | * Use cases | 45 | * Use cases |
47 | * --------- | 46 | * --------- |
48 | * | 47 | * |
49 | * Unless stated otherwise, all operations which modify the irq buffers queue | 48 | * Unless stated otherwise, all operations that modify the irq buffers queue |
50 | * are protected by the irq spinlock. | 49 | * are protected by the irq spinlock. |
51 | * | 50 | * |
52 | * 1. The user queues the buffers, starts streaming and dequeues a buffer. | 51 | * 1. The user queues the buffers, starts streaming and dequeues a buffer. |
53 | * | 52 | * |
54 | * The buffers are added to the main and irq queues. Both operations are | 53 | * The buffers are added to the main and irq queues. Both operations are |
55 | * protected by the queue lock, and the latert is protected by the irq | 54 | * protected by the queue lock, and the later is protected by the irq |
56 | * spinlock as well. | 55 | * spinlock as well. |
57 | * | 56 | * |
58 | * The completion handler fetches a buffer from the irq queue and fills it | 57 | * The completion handler fetches a buffer from the irq queue and fills it |
@@ -60,7 +59,7 @@ | |||
60 | * returns immediately. | 59 | * returns immediately. |
61 | * | 60 | * |
62 | * When the buffer is full, the completion handler removes it from the irq | 61 | * When the buffer is full, the completion handler removes it from the irq |
63 | * queue, marks it as ready (UVC_BUF_STATE_DONE) and wake its wait queue. | 62 | * queue, marks it as ready (UVC_BUF_STATE_DONE) and wakes its wait queue. |
64 | * At that point, any process waiting on the buffer will be woken up. If a | 63 | * At that point, any process waiting on the buffer will be woken up. If a |
65 | * process tries to dequeue a buffer after it has been marked ready, the | 64 | * process tries to dequeue a buffer after it has been marked ready, the |
66 | * dequeing will succeed immediately. | 65 | * dequeing will succeed immediately. |
@@ -91,8 +90,8 @@ void uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type) | |||
91 | /* | 90 | /* |
92 | * Allocate the video buffers. | 91 | * Allocate the video buffers. |
93 | * | 92 | * |
94 | * Pages are reserved to make sure they will not be swaped, as they will be | 93 | * Pages are reserved to make sure they will not be swapped, as they will be |
95 | * filled in URB completion handler. | 94 | * filled in the URB completion handler. |
96 | * | 95 | * |
97 | * Buffers will be individually mapped, so they must all be page aligned. | 96 | * Buffers will be individually mapped, so they must all be page aligned. |
98 | */ | 97 | */ |
@@ -210,8 +209,8 @@ int uvc_query_buffer(struct uvc_video_queue *queue, | |||
210 | __uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf); | 209 | __uvc_query_buffer(&queue->buffer[v4l2_buf->index], v4l2_buf); |
211 | 210 | ||
212 | done: | 211 | done: |
213 | mutex_unlock(&queue->mutex); | 212 | mutex_unlock(&queue->mutex); |
214 | return ret; | 213 | return ret; |
215 | } | 214 | } |
216 | 215 | ||
217 | /* | 216 | /* |
@@ -236,7 +235,7 @@ int uvc_queue_buffer(struct uvc_video_queue *queue, | |||
236 | } | 235 | } |
237 | 236 | ||
238 | mutex_lock(&queue->mutex); | 237 | mutex_lock(&queue->mutex); |
239 | if (v4l2_buf->index >= queue->count) { | 238 | if (v4l2_buf->index >= queue->count) { |
240 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n"); | 239 | uvc_trace(UVC_TRACE_CAPTURE, "[E] Out of range index.\n"); |
241 | ret = -EINVAL; | 240 | ret = -EINVAL; |
242 | goto done; | 241 | goto done; |
@@ -429,7 +428,7 @@ done: | |||
429 | * Cancel the video buffers queue. | 428 | * Cancel the video buffers queue. |
430 | * | 429 | * |
431 | * Cancelling the queue marks all buffers on the irq queue as erroneous, | 430 | * Cancelling the queue marks all buffers on the irq queue as erroneous, |
432 | * wakes them up and remove them from the queue. | 431 | * wakes them up and removes them from the queue. |
433 | * | 432 | * |
434 | * If the disconnect parameter is set, further calls to uvc_queue_buffer will | 433 | * If the disconnect parameter is set, further calls to uvc_queue_buffer will |
435 | * fail with -ENODEV. | 434 | * fail with -ENODEV. |