2 * uvc_video.c -- USB Video Class Gadget driver
4 * Copyright (C) 2009-2010
5 * Laurent Pinchart (laurent.pinchart@ideasonboard.com)
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.
13 #include <linux/kernel.h>
14 #include <linux/device.h>
15 #include <linux/errno.h>
16 #include <linux/usb/ch9.h>
17 #include <linux/usb/gadget.h>
18 #include <linux/usb/video.h>
20 #include <media/v4l2-dev.h>
23 #include "uvc_queue.h"
25 /* --------------------------------------------------------------------------
30 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
34 data[1] = UVC_STREAM_EOH | video->fid;
36 if (buf->bytesused - video->queue.buf_used <= len - 2)
37 data[1] |= UVC_STREAM_EOF;
43 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
46 struct uvc_video_queue *queue = &video->queue;
50 /* Copy video data to the USB buffer. */
51 mem = buf->mem + queue->buf_used;
52 nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
54 memcpy(data, mem, nbytes);
55 queue->buf_used += nbytes;
61 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
62 struct uvc_buffer *buf)
65 int len = video->req_size;
68 /* Add a header at the beginning of the payload. */
69 if (video->payload_size == 0) {
70 ret = uvc_video_encode_header(video, buf, mem, len);
71 video->payload_size += ret;
76 /* Process video data. */
77 len = min((int)(video->max_payload_size - video->payload_size), len);
78 ret = uvc_video_encode_data(video, buf, mem, len);
80 video->payload_size += ret;
83 req->length = video->req_size - len;
84 req->zero = video->payload_size == video->max_payload_size;
86 if (buf->bytesused == video->queue.buf_used) {
87 video->queue.buf_used = 0;
88 buf->state = UVC_BUF_STATE_DONE;
89 uvcg_queue_next_buffer(&video->queue, buf);
90 video->fid ^= UVC_STREAM_FID;
92 video->payload_size = 0;
95 if (video->payload_size == video->max_payload_size ||
96 buf->bytesused == video->queue.buf_used)
97 video->payload_size = 0;
101 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
102 struct uvc_buffer *buf)
104 void *mem = req->buf;
105 int len = video->req_size;
108 /* Add the header. */
109 ret = uvc_video_encode_header(video, buf, mem, len);
113 /* Process video data. */
114 ret = uvc_video_encode_data(video, buf, mem, len);
117 req->length = video->req_size - len;
119 if (buf->bytesused == video->queue.buf_used) {
120 video->queue.buf_used = 0;
121 buf->state = UVC_BUF_STATE_DONE;
122 uvcg_queue_next_buffer(&video->queue, buf);
123 video->fid ^= UVC_STREAM_FID;
127 /* --------------------------------------------------------------------------
132 * I somehow feel that synchronisation won't be easy to achieve here. We have
133 * three events that control USB requests submission:
135 * - USB request completion: the completion handler will resubmit the request
136 * if a video buffer is available.
138 * - USB interface setting selection: in response to a SET_INTERFACE request,
139 * the handler will start streaming if a video buffer is available and if
140 * video is not currently streaming.
142 * - V4L2 buffer queueing: the driver will start streaming if video is not
143 * currently streaming.
145 * Race conditions between those 3 events might lead to deadlocks or other
146 * nasty side effects.
148 * The "video currently streaming" condition can't be detected by the irqqueue
149 * being empty, as a request can still be in flight. A separate "queue paused"
150 * flag is thus needed.
152 * The paused flag will be set when we try to retrieve the irqqueue head if the
153 * queue is empty, and cleared when we queue a buffer.
155 * The USB request completion handler will get the buffer at the irqqueue head
156 * under protection of the queue spinlock. If the queue is empty, the streaming
157 * paused flag will be set. Right after releasing the spinlock a userspace
158 * application can queue a buffer. The flag will then cleared, and the ioctl
159 * handler will restart the video stream.
162 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
164 struct uvc_video *video = req->context;
165 struct uvc_video_queue *queue = &video->queue;
166 struct uvc_buffer *buf;
170 switch (req->status) {
174 case -ESHUTDOWN: /* disconnect from host. */
175 printk(KERN_DEBUG "VS request cancelled.\n");
176 uvcg_queue_cancel(queue, 1);
180 printk(KERN_INFO "VS request completed with status %d.\n",
182 uvcg_queue_cancel(queue, 0);
186 spin_lock_irqsave(&video->queue.irqlock, flags);
187 buf = uvcg_queue_head(&video->queue);
189 spin_unlock_irqrestore(&video->queue.irqlock, flags);
193 video->encode(req, video, buf);
195 if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
196 printk(KERN_INFO "Failed to queue request (%d).\n", ret);
198 spin_unlock_irqrestore(&video->queue.irqlock, flags);
199 uvcg_queue_cancel(queue, 0);
202 spin_unlock_irqrestore(&video->queue.irqlock, flags);
207 spin_lock_irqsave(&video->req_lock, flags);
208 list_add_tail(&req->list, &video->req_free);
209 spin_unlock_irqrestore(&video->req_lock, flags);
213 uvc_video_free_requests(struct uvc_video *video)
217 for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
219 usb_ep_free_request(video->ep, video->req[i]);
220 video->req[i] = NULL;
223 if (video->req_buffer[i]) {
224 kfree(video->req_buffer[i]);
225 video->req_buffer[i] = NULL;
229 INIT_LIST_HEAD(&video->req_free);
235 uvc_video_alloc_requests(struct uvc_video *video)
237 unsigned int req_size;
241 BUG_ON(video->req_size);
243 req_size = video->ep->maxpacket
244 * max_t(unsigned int, video->ep->maxburst, 1)
245 * (video->ep->mult + 1);
247 for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
248 video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
249 if (video->req_buffer[i] == NULL)
252 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
253 if (video->req[i] == NULL)
256 video->req[i]->buf = video->req_buffer[i];
257 video->req[i]->length = 0;
258 video->req[i]->complete = uvc_video_complete;
259 video->req[i]->context = video;
261 list_add_tail(&video->req[i]->list, &video->req_free);
264 video->req_size = req_size;
269 uvc_video_free_requests(video);
273 /* --------------------------------------------------------------------------
278 * uvcg_video_pump - Pump video data into the USB requests
280 * This function fills the available USB requests (listed in req_free) with
281 * video data from the queued buffers.
283 int uvcg_video_pump(struct uvc_video *video)
285 struct uvc_video_queue *queue = &video->queue;
286 struct usb_request *req;
287 struct uvc_buffer *buf;
291 /* FIXME TODO Race between uvcg_video_pump and requests completion
296 /* Retrieve the first available USB request, protected by the
299 spin_lock_irqsave(&video->req_lock, flags);
300 if (list_empty(&video->req_free)) {
301 spin_unlock_irqrestore(&video->req_lock, flags);
304 req = list_first_entry(&video->req_free, struct usb_request,
306 list_del(&req->list);
307 spin_unlock_irqrestore(&video->req_lock, flags);
309 /* Retrieve the first available video buffer and fill the
310 * request, protected by the video queue irqlock.
312 spin_lock_irqsave(&queue->irqlock, flags);
313 buf = uvcg_queue_head(queue);
315 spin_unlock_irqrestore(&queue->irqlock, flags);
319 video->encode(req, video, buf);
321 /* Queue the USB request */
322 ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
324 printk(KERN_INFO "Failed to queue request (%d)\n", ret);
325 usb_ep_set_halt(video->ep);
326 spin_unlock_irqrestore(&queue->irqlock, flags);
327 uvcg_queue_cancel(queue, 0);
330 spin_unlock_irqrestore(&queue->irqlock, flags);
333 spin_lock_irqsave(&video->req_lock, flags);
334 list_add_tail(&req->list, &video->req_free);
335 spin_unlock_irqrestore(&video->req_lock, flags);
340 * Enable or disable the video stream.
342 int uvcg_video_enable(struct uvc_video *video, int enable)
347 if (video->ep == NULL) {
348 printk(KERN_INFO "Video enable failed, device is "
354 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
355 usb_ep_dequeue(video->ep, video->req[i]);
357 uvc_video_free_requests(video);
358 uvcg_queue_enable(&video->queue, 0);
362 if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
365 if ((ret = uvc_video_alloc_requests(video)) < 0)
368 if (video->max_payload_size) {
369 video->encode = uvc_video_encode_bulk;
370 video->payload_size = 0;
372 video->encode = uvc_video_encode_isoc;
374 return uvcg_video_pump(video);
378 * Initialize the UVC video stream.
380 int uvcg_video_init(struct uvc_video *video)
382 INIT_LIST_HEAD(&video->req_free);
383 spin_lock_init(&video->req_lock);
385 video->fcc = V4L2_PIX_FMT_YUYV;
389 video->imagesize = 320 * 240 * 2;
391 /* Initialize the video buffers queue. */
392 uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);