Le samedi 02 février 2019 à 18:03 +0100, Hans Verkuil a écrit :
> Stateless codecs have to find buffers based on a timestamp (vb2_find_timestamp).
> The timestamp is set to 0 initially, so prohibit finding timestamp 0 since it
> could find unused buffers without associated memory (userptr or dmabuf).
>
> The memory associated with a buffer will also disappear if the same buffer was
> requeued with a different userptr address or dmabuf fd. Detect this and set the
> timestamp of that buffer to 0 if this happens.
Just a small concern, does it mean 0 is considered an invalid timestamp
? In streaming it would be quite normal for a first picture to have PTS
0.
Nicolas
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> ---
> Note: I think it is still necessary to lock a buffer when it is in use as
> a reference frame, otherwise a userspace application can queue it again with
> a different dmabuf fd, which could free the memory of the old dmabuf.
>
> vb2_find_buffer should probably do that.
> ---
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index e07b6bdb6982..b664d9790330 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -1043,6 +1043,8 @@ static int __prepare_userptr(struct vb2_buffer *vb)
> reacquired = true;
> call_void_vb_qop(vb, buf_cleanup, vb);
> }
> + if (!q->is_output)
> + vb->timestamp = 0;
> call_void_memop(vb, put_userptr, vb->planes[plane].mem_priv);
> }
>
> @@ -1157,6 +1159,8 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
> /* Skip the plane if already verified */
> if (dbuf == vb->planes[plane].dbuf &&
> vb->planes[plane].length == planes[plane].length) {
> + if (!q->is_output)
> + vb->timestamp = 0;
> dma_buf_put(dbuf);
> continue;
> }
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 3aeaea3af42a..8e966fa81b7e 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -603,6 +603,9 @@ int vb2_find_timestamp(const struct vb2_queue *q, u64 timestamp,
> {
> unsigned int i;
>
> + if (!timestamp)
> + return -1;
> +
> for (i = start_idx; i < q->num_buffers; i++)
> if (q->bufs[i]->timestamp == timestamp)
> return i;
> diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
> index 8a10889dc2fd..01bf4b2199c7 100644
> --- a/include/media/videobuf2-v4l2.h
> +++ b/include/media/videobuf2-v4l2.h
> @@ -59,14 +59,14 @@ struct vb2_v4l2_buffer {
> * vb2_find_timestamp() - Find buffer with given timestamp in the queue
> *
> * @q: pointer to &struct vb2_queue with videobuf2 queue.
> - * @timestamp: the timestamp to find.
> + * @timestamp: the timestamp to find. Must be > 0.
> * @start_idx: the start index (usually 0) in the buffer array to start
> * searching from. Note that there may be multiple buffers
> * with the same timestamp value, so you can restart the search
> * by setting @start_idx to the previously found index + 1.
> *
> * Returns the buffer index of the buffer with the given @timestamp, or
> - * -1 if no buffer with @timestamp was found.
> + * -1 if no buffer with @timestamp was found or if @timestamp was 0.
> */
> int vb2_find_timestamp(const struct vb2_queue *q, u64 timestamp,
> unsigned int start_idx);
