[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: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 73824a5ada83788fff9b143b36cf0eff5cec24bc..cbef15c07e5359a2fbe559fcccdaae3f114f265d 100644 (file)
--- 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 20cdbc0900ea5e0a9ecd4b4f416c3a1ded485a34..552d7e127c39864dff59d7cda8e9d694413b08c9 100644 (file)
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -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.

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index a5790fd5d12500aa3abac79a8271b1e0fb9ea2ba..22a44c2f596380856acb1bccf95f14d0c2144994 100644 (file)
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -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,