return ret;
}
-/*
- * I somehow feel that synchronisation won't be easy to achieve here. We have
- * three events that control USB requests submission:
- *
- * - USB request completion: the completion handler will resubmit the request
- * if a video buffer is available.
- *
- * - USB interface setting selection: in response to a SET_INTERFACE request,
- * the handler will start streaming if a video buffer is available and if
- * video is not currently streaming.
- *
- * - V4L2 buffer queueing: the driver will start streaming if video is not
- * currently streaming.
- *
- * Race conditions between those 3 events might lead to deadlocks or other
- * nasty side effects.
- *
- * The "video currently streaming" condition can't be detected by the irqqueue
- * being empty, as a request can still be in flight. A separate "queue paused"
- * flag is thus needed.
- *
- * The paused flag will be set when we try to retrieve the irqqueue head if the
- * queue is empty, and cleared when we queue a buffer.
- *
- * The USB request completion handler will get the buffer at the irqqueue head
- * under protection of the queue spinlock. If the queue is empty, the streaming
- * paused flag will be set. Right after releasing the spinlock a userspace
- * application can queue a buffer. The flag will then cleared, and the ioctl
- * handler will restart the video stream.
- */
static void
uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
{
struct uvc_video *video = req->context;
struct uvc_video_queue *queue = &video->queue;
- struct uvc_buffer *buf;
unsigned long flags;
- int ret;
switch (req->status) {
case 0:
case -ESHUTDOWN: /* disconnect from host. */
uvcg_dbg(&video->uvc->func, "VS request cancelled.\n");
uvcg_queue_cancel(queue, 1);
- goto requeue;
+ break;
default:
uvcg_info(&video->uvc->func,
"VS request completed with status %d.\n",
req->status);
uvcg_queue_cancel(queue, 0);
- goto requeue;
}
- spin_lock_irqsave(&video->queue.irqlock, flags);
- buf = uvcg_queue_head(&video->queue);
- if (buf == NULL) {
- spin_unlock_irqrestore(&video->queue.irqlock, flags);
- goto requeue;
- }
-
- video->encode(req, video, buf);
-
- ret = uvcg_video_ep_queue(video, req);
- spin_unlock_irqrestore(&video->queue.irqlock, flags);
-
- if (ret < 0) {
- uvcg_queue_cancel(queue, 0);
- goto requeue;
- }
-
- return;
-
-requeue:
spin_lock_irqsave(&video->req_lock, flags);
list_add_tail(&req->list, &video->req_free);
spin_unlock_irqrestore(&video->req_lock, flags);
+
+ schedule_work(&video->pump);
}
static int
* This function fills the available USB requests (listed in req_free) with
* video data from the queued buffers.
*/
-int uvcg_video_pump(struct uvc_video *video)
+static void uvcg_video_pump(struct work_struct *work)
{
+ struct uvc_video *video = container_of(work, struct uvc_video, pump);
struct uvc_video_queue *queue = &video->queue;
struct usb_request *req;
struct uvc_buffer *buf;
unsigned long flags;
int ret;
- /* FIXME TODO Race between uvcg_video_pump and requests completion
- * handler ???
- */
-
while (1) {
/* Retrieve the first available USB request, protected by the
* request lock.
spin_lock_irqsave(&video->req_lock, flags);
if (list_empty(&video->req_free)) {
spin_unlock_irqrestore(&video->req_lock, flags);
- return 0;
+ return;
}
req = list_first_entry(&video->req_free, struct usb_request,
list);
spin_lock_irqsave(&video->req_lock, flags);
list_add_tail(&req->list, &video->req_free);
spin_unlock_irqrestore(&video->req_lock, flags);
- return 0;
+ return;
}
/*
}
if (!enable) {
+ cancel_work_sync(&video->pump);
+ uvcg_queue_cancel(&video->queue, 0);
+
for (i = 0; i < UVC_NUM_REQUESTS; ++i)
if (video->req[i])
usb_ep_dequeue(video->ep, video->req[i]);
} else
video->encode = uvc_video_encode_isoc;
- return uvcg_video_pump(video);
+ schedule_work(&video->pump);
+
+ return ret;
}
/*
{
INIT_LIST_HEAD(&video->req_free);
spin_lock_init(&video->req_lock);
+ INIT_WORK(&video->pump, uvcg_video_pump);
video->uvc = uvc;
video->fcc = V4L2_PIX_FMT_YUYV;