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Commit c1621840 authored by Philipp Zabel's avatar Philipp Zabel Committed by Mauro Carvalho Chehab
Browse files

[media] videobuf2: return -EPIPE from DQBUF after the last buffer 



If the last buffer was dequeued from a capture queue, let poll return
immediately and let DQBUF return -EPIPE to signal there will no more
buffers to dequeue until STREAMOFF.
The driver signals the last buffer by setting the V4L2_BUF_FLAG_LAST.
To reenable dequeuing on the capture queue, the driver must explicitly
call vb2_clear_last_buffer_queued. The last buffer queued flag is
cleared automatically during STREAMOFF.

Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Acked-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarKamil Debski <k.debski@samsung.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent dc199241

drivers/media/v4l2-core/v4l2-mem2mem.c

+9 −1
Original line number Diff line number Diff line
@@ -564,8 +564,16 @@ unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx, 


	if (list_empty(&src_q->done_list))

		poll_wait(file, &src_q->done_wq, wait);

	if (list_empty(&dst_q->done_list))

	if (list_empty(&dst_q->done_list)) {

		/*

		 * If the last buffer was dequeued from the capture queue,

		 * return immediately. DQBUF will return -EPIPE.

		 */

		if (dst_q->last_buffer_dequeued)

			return rc | POLLIN | POLLRDNORM;



		poll_wait(file, &dst_q->done_wq, wait);

	}



	if (m2m_ctx->m2m_dev->m2m_ops->lock)

		m2m_ctx->m2m_dev->m2m_ops->lock(m2m_ctx->priv);

drivers/media/v4l2-core/videobuf2-core.c

+18 −1
Original line number Diff line number Diff line
@@ -1943,6 +1943,11 @@ static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking) 
			return -EIO;

		}



		if (q->last_buffer_dequeued) {

			dprintk(3, "last buffer dequeued already, will not wait for buffers\n");

			return -EPIPE;

		}



		if (!list_empty(&q->done_list)) {

			/*

			 * Found a buffer that we were waiting for.
@@ -2098,6 +2103,9 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n 
	/* Remove from videobuf queue */

	list_del(&vb->queued_entry);

	q->queued_count--;

	if (!V4L2_TYPE_IS_OUTPUT(q->type) &&

	    vb->v4l2_buf.flags & V4L2_BUF_FLAG_LAST)

		q->last_buffer_dequeued = true;

	/* go back to dequeued state */

	__vb2_dqbuf(vb);
@@ -2311,6 +2319,7 @@ static int vb2_internal_streamoff(struct vb2_queue *q, enum v4l2_buf_type type) 
	 */

	__vb2_queue_cancel(q);

	q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);

	q->last_buffer_dequeued = false;



	dprintk(3, "successful\n");

	return 0;
@@ -2653,8 +2662,16 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) 
	if (V4L2_TYPE_IS_OUTPUT(q->type) && q->queued_count < q->num_buffers)

		return res | POLLOUT | POLLWRNORM;



	if (list_empty(&q->done_list))

	if (list_empty(&q->done_list)) {

		/*

		 * If the last buffer was dequeued from a capture queue,

		 * return immediately. DQBUF will return -EPIPE.

		 */

		if (q->last_buffer_dequeued)

			return res | POLLIN | POLLRDNORM;



		poll_wait(file, &q->done_wq, wait);

	}



	/*

	 * Take first buffer available for dequeuing.

include/media/videobuf2-core.h

+13 −0
Original line number Diff line number Diff line
@@ -381,6 +381,9 @@ struct v4l2_fh; 
 * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for

 *		buffers. Only set for capture queues if qbuf has not yet been

 *		called since poll() needs to return POLLERR in that situation.

 * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the

 *		last decoded buffer was already dequeued. Set for capture queues

 *		when a buffer with the V4L2_BUF_FLAG_LAST is dequeued.

 * @fileio:	file io emulator internal data, used only if emulator is active

 * @threadio:	thread io internal data, used only if thread is active

 */
@@ -423,6 +426,7 @@ struct vb2_queue { 
	unsigned int			start_streaming_called:1;

	unsigned int			error:1;

	unsigned int			waiting_for_buffers:1;

	unsigned int			last_buffer_dequeued:1;



	struct vb2_fileio_data		*fileio;

	struct vb2_threadio_data	*threadio;
@@ -603,6 +607,15 @@ static inline bool vb2_start_streaming_called(struct vb2_queue *q) 
	return q->start_streaming_called;

}



/**

 * vb2_clear_last_buffer_dequeued() - clear last buffer dequeued flag of queue

 * @q:		videobuf queue

 */

static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)

{

	q->last_buffer_dequeued = false;

}



/*

 * The following functions are not part of the vb2 core API, but are simple

 * helper functions that you can use in your struct v4l2_file_operations,