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.
Signed-off-by: Philipp Zabel <p.za...@pengutronix.de>
---
TODO: (How) should the last_buffer_dequeud flag be cleared in reaction to
V4L2_DEC_CMD_START?
---
drivers/media/v4l2-core/v4l2-mem2mem.c | 10 +++++++++-
drivers/media/v4l2-core/videobuf2-core.c | 18 +++++++++++++++++-
include/media/videobuf2-core.h | 1 +
3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c
b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 80c588f..1b5b432 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -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);
diff --git a/drivers/media/v4l2-core/videobuf2-core.c
b/drivers/media/v4l2-core/videobuf2-core.c
index d09a891..c2c2eac 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2046,6 +2046,10 @@ static int vb2_internal_dqbuf(struct vb2_queue *q,
struct v4l2_buffer *b, bool n
struct vb2_buffer *vb = NULL;
int ret;
+ if (q->last_buffer_dequeued) {
+ dprintk(3, "last buffer dequeued already\n");
+ return -EPIPE;
+ }
if (b->type != q->type) {
dprintk(1, "invalid buffer type\n");
return -EINVAL;
@@ -2073,6 +2077,9 @@ 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);
@@ -2286,6 +2293,7 @@ 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;
@@ -2628,8 +2636,16 @@ 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 (!V4L2_TYPE_IS_OUTPUT(q->type) && q->last_buffer_dequeued)
+ return res | POLLIN | POLLRDNORM;
+
poll_wait(file, &q->done_wq, wait);
+ }
/*
* Take first buffer available for dequeuing.
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index bd2cec2..ca337bf 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -429,6 +429,7 @@ 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;
--
2.1.4
--
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