1 // SPDX-License-Identifier: GPL-2.0+
3 * uvc_video.c -- USB Video Class Gadget driver
5 * Copyright (C) 2009-2010
6 * Laurent Pinchart (laurent.pinchart@ideasonboard.com)
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>
16 #include <media/v4l2-dev.h>
19 #include "uvc_queue.h"
20 #include "uvc_video.h"
22 /* --------------------------------------------------------------------------
27 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
31 data[1] = UVC_STREAM_EOH | video->fid;
33 if (buf->bytesused - video->queue.buf_used <= len - 2)
34 data[1] |= UVC_STREAM_EOF;
40 uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
43 struct uvc_video_queue *queue = &video->queue;
47 /* Copy video data to the USB buffer. */
48 mem = buf->mem + queue->buf_used;
49 nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
51 memcpy(data, mem, nbytes);
52 queue->buf_used += nbytes;
58 uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
59 struct uvc_buffer *buf)
62 int len = video->req_size;
65 /* Add a header at the beginning of the payload. */
66 if (video->payload_size == 0) {
67 ret = uvc_video_encode_header(video, buf, mem, len);
68 video->payload_size += ret;
73 /* Process video data. */
74 len = min((int)(video->max_payload_size - video->payload_size), len);
75 ret = uvc_video_encode_data(video, buf, mem, len);
77 video->payload_size += ret;
80 req->length = video->req_size - len;
81 req->zero = video->payload_size == video->max_payload_size;
83 if (buf->bytesused == video->queue.buf_used) {
84 video->queue.buf_used = 0;
85 buf->state = UVC_BUF_STATE_DONE;
86 uvcg_queue_next_buffer(&video->queue, buf);
87 video->fid ^= UVC_STREAM_FID;
89 video->payload_size = 0;
92 if (video->payload_size == video->max_payload_size ||
93 buf->bytesused == video->queue.buf_used)
94 video->payload_size = 0;
98 uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
99 struct uvc_buffer *buf)
101 void *mem = req->buf;
102 int len = video->req_size;
105 /* Add the header. */
106 ret = uvc_video_encode_header(video, buf, mem, len);
110 /* Process video data. */
111 ret = uvc_video_encode_data(video, buf, mem, len);
114 req->length = video->req_size - len;
116 if (buf->bytesused == video->queue.buf_used) {
117 video->queue.buf_used = 0;
118 buf->state = UVC_BUF_STATE_DONE;
119 uvcg_queue_next_buffer(&video->queue, buf);
120 video->fid ^= UVC_STREAM_FID;
124 /* --------------------------------------------------------------------------
128 static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req)
132 ret = usb_ep_queue(video->ep, req, GFP_ATOMIC);
134 printk(KERN_INFO "Failed to queue request (%d).\n", ret);
135 /* Isochronous endpoints can't be halted. */
136 if (usb_endpoint_xfer_bulk(video->ep->desc))
137 usb_ep_set_halt(video->ep);
144 * I somehow feel that synchronisation won't be easy to achieve here. We have
145 * three events that control USB requests submission:
147 * - USB request completion: the completion handler will resubmit the request
148 * if a video buffer is available.
150 * - USB interface setting selection: in response to a SET_INTERFACE request,
151 * the handler will start streaming if a video buffer is available and if
152 * video is not currently streaming.
154 * - V4L2 buffer queueing: the driver will start streaming if video is not
155 * currently streaming.
157 * Race conditions between those 3 events might lead to deadlocks or other
158 * nasty side effects.
160 * The "video currently streaming" condition can't be detected by the irqqueue
161 * being empty, as a request can still be in flight. A separate "queue paused"
162 * flag is thus needed.
164 * The paused flag will be set when we try to retrieve the irqqueue head if the
165 * queue is empty, and cleared when we queue a buffer.
167 * The USB request completion handler will get the buffer at the irqqueue head
168 * under protection of the queue spinlock. If the queue is empty, the streaming
169 * paused flag will be set. Right after releasing the spinlock a userspace
170 * application can queue a buffer. The flag will then cleared, and the ioctl
171 * handler will restart the video stream.
174 uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
176 struct uvc_video *video = req->context;
177 struct uvc_video_queue *queue = &video->queue;
178 struct uvc_buffer *buf;
182 switch (req->status) {
186 case -ESHUTDOWN: /* disconnect from host. */
187 printk(KERN_DEBUG "VS request cancelled.\n");
188 uvcg_queue_cancel(queue, 1);
192 printk(KERN_INFO "VS request completed with status %d.\n",
194 uvcg_queue_cancel(queue, 0);
198 spin_lock_irqsave(&video->queue.irqlock, flags);
199 buf = uvcg_queue_head(&video->queue);
201 spin_unlock_irqrestore(&video->queue.irqlock, flags);
205 video->encode(req, video, buf);
207 ret = uvcg_video_ep_queue(video, req);
208 spin_unlock_irqrestore(&video->queue.irqlock, flags);
211 uvcg_queue_cancel(queue, 0);
218 spin_lock_irqsave(&video->req_lock, flags);
219 list_add_tail(&req->list, &video->req_free);
220 spin_unlock_irqrestore(&video->req_lock, flags);
224 uvc_video_free_requests(struct uvc_video *video)
228 for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
230 usb_ep_free_request(video->ep, video->req[i]);
231 video->req[i] = NULL;
234 if (video->req_buffer[i]) {
235 kfree(video->req_buffer[i]);
236 video->req_buffer[i] = NULL;
240 INIT_LIST_HEAD(&video->req_free);
246 uvc_video_alloc_requests(struct uvc_video *video)
248 unsigned int req_size;
252 BUG_ON(video->req_size);
254 req_size = video->ep->maxpacket
255 * max_t(unsigned int, video->ep->maxburst, 1)
258 for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
259 video->req_buffer[i] = kmalloc(req_size, GFP_KERNEL);
260 if (video->req_buffer[i] == NULL)
263 video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
264 if (video->req[i] == NULL)
267 video->req[i]->buf = video->req_buffer[i];
268 video->req[i]->length = 0;
269 video->req[i]->complete = uvc_video_complete;
270 video->req[i]->context = video;
272 list_add_tail(&video->req[i]->list, &video->req_free);
275 video->req_size = req_size;
280 uvc_video_free_requests(video);
284 /* --------------------------------------------------------------------------
289 * uvcg_video_pump - Pump video data into the USB requests
291 * This function fills the available USB requests (listed in req_free) with
292 * video data from the queued buffers.
294 int uvcg_video_pump(struct uvc_video *video)
296 struct uvc_video_queue *queue = &video->queue;
297 struct usb_request *req;
298 struct uvc_buffer *buf;
302 /* FIXME TODO Race between uvcg_video_pump and requests completion
307 /* Retrieve the first available USB request, protected by the
310 spin_lock_irqsave(&video->req_lock, flags);
311 if (list_empty(&video->req_free)) {
312 spin_unlock_irqrestore(&video->req_lock, flags);
315 req = list_first_entry(&video->req_free, struct usb_request,
317 list_del(&req->list);
318 spin_unlock_irqrestore(&video->req_lock, flags);
320 /* Retrieve the first available video buffer and fill the
321 * request, protected by the video queue irqlock.
323 spin_lock_irqsave(&queue->irqlock, flags);
324 buf = uvcg_queue_head(queue);
326 spin_unlock_irqrestore(&queue->irqlock, flags);
330 video->encode(req, video, buf);
332 /* Queue the USB request */
333 ret = uvcg_video_ep_queue(video, req);
334 spin_unlock_irqrestore(&queue->irqlock, flags);
337 uvcg_queue_cancel(queue, 0);
342 spin_lock_irqsave(&video->req_lock, flags);
343 list_add_tail(&req->list, &video->req_free);
344 spin_unlock_irqrestore(&video->req_lock, flags);
349 * Enable or disable the video stream.
351 int uvcg_video_enable(struct uvc_video *video, int enable)
356 if (video->ep == NULL) {
357 printk(KERN_INFO "Video enable failed, device is "
363 for (i = 0; i < UVC_NUM_REQUESTS; ++i)
365 usb_ep_dequeue(video->ep, video->req[i]);
367 uvc_video_free_requests(video);
368 uvcg_queue_enable(&video->queue, 0);
372 if ((ret = uvcg_queue_enable(&video->queue, 1)) < 0)
375 if ((ret = uvc_video_alloc_requests(video)) < 0)
378 if (video->max_payload_size) {
379 video->encode = uvc_video_encode_bulk;
380 video->payload_size = 0;
382 video->encode = uvc_video_encode_isoc;
384 return uvcg_video_pump(video);
388 * Initialize the UVC video stream.
390 int uvcg_video_init(struct uvc_video *video)
392 INIT_LIST_HEAD(&video->req_free);
393 spin_lock_init(&video->req_lock);
395 video->fcc = V4L2_PIX_FMT_YUYV;
399 video->imagesize = 320 * 240 * 2;
401 /* Initialize the video buffers queue. */
402 uvcg_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT,