Hi Kamil,
On 12/16/14 12:36, Kamil Debski wrote:
> The vb2: fix bytesused == 0 handling (8a75ffb) patch changed the behavior
> of __fill_vb2_buffer function, so that if bytesused is 0 it is set to the
> size of the buffer. However, bytesused set to 0 is used by older codec
> drivers as as indication used to mark the end of stream.
>
> To keep backward compatibility, this patch adds a flag passed to the
> vb2_queue_init function - VB2_FILEIO_ALLOW_ZERO_BYTESUSED. If the flag is
> set upon initialization of the queue, the videobuf2 keeps the value of
> bytesused intact and passes it to the driver.
What is the status of this patch series?
Note that io_flags is really the wrong place for this flag, it should
be io_modes. This flag has nothing to do with file I/O.
Regards,
Hans
>
> Reported-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> Signed-off-by: Kamil Debski <k.debski@xxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 33 ++++++++++++++++++++++++------
> include/media/videobuf2-core.h | 3 +++
> 2 files changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index d09a891..1068dbb 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1276,13 +1276,23 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
> * userspace clearly never bothered to set it and
> * it's a safe assumption that they really meant to
> * use the full plane sizes.
> + *
> + * Some drivers, e.g. old codec drivers, use bytesused
> + * == 0 as a way to indicate that streaming is finished.
> + * In that case, the driver should use the following
> + * io_flag VB2_FILEIO_ALLOW_ZERO_BYTESUSED to keep old
> + * userspace applications working.
> */
> for (plane = 0; plane < vb->num_planes; ++plane) {
> struct v4l2_plane *pdst = &v4l2_planes[plane];
> struct v4l2_plane *psrc = &b->m.planes[plane];
>
> - pdst->bytesused = psrc->bytesused ?
> - psrc->bytesused : pdst->length;
> + if (vb->vb2_queue->io_flags &
> + VB2_FILEIO_ALLOW_ZERO_BYTESUSED)
> + pdst->bytesused = psrc->bytesused;
> + else
> + pdst->bytesused = psrc->bytesused ?
> + psrc->bytesused : pdst->length;
> pdst->data_offset = psrc->data_offset;
> }
> }
> @@ -1295,6 +1305,12 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
> *
> * If bytesused == 0 for the output buffer, then fall back
> * to the full buffer size as that's a sensible default.
> + *
> + * Some drivers, e.g. old codec drivers, use bytesused == 0
> + * as a way to indicate that streaming is finished. In that
> + * case, the driver should use the following io_flag
> + * VB2_FILEIO_ALLOW_ZERO_BYTESUSED to keep old userspace
> + * applications working.
> */
> if (b->memory == V4L2_MEMORY_USERPTR) {
> v4l2_planes[0].m.userptr = b->m.userptr;
> @@ -1306,11 +1322,16 @@ static void __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b
> v4l2_planes[0].length = b->length;
> }
>
> - if (V4L2_TYPE_IS_OUTPUT(b->type))
> - v4l2_planes[0].bytesused = b->bytesused ?
> - b->bytesused : v4l2_planes[0].length;
> - else
> + if (V4L2_TYPE_IS_OUTPUT(b->type)) {
> + if (vb->vb2_queue->io_flags &
> + VB2_FILEIO_ALLOW_ZERO_BYTESUSED)
> + v4l2_planes[0].bytesused = b->bytesused;
> + else
> + v4l2_planes[0].bytesused = b->bytesused ?
> + b->bytesused : v4l2_planes[0].length;
> + } else {
> v4l2_planes[0].bytesused = 0;
> + }
>
> }
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index bd2cec2..0540bc3 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -138,10 +138,13 @@ enum vb2_io_modes {
> * by default the 'streaming' style is used by the file io emulator
> * @VB2_FILEIO_READ_ONCE: report EOF after reading the first buffer
> * @VB2_FILEIO_WRITE_IMMEDIATELY: queue buffer after each write() call
> + * @VB2_FILEIO_ALLOW_ZERO_BYTESUSED: the driver setting this flag will handle
> + * bytesused == 0 as a special case
> */
> enum vb2_fileio_flags {
> VB2_FILEIO_READ_ONCE = (1 << 0),
> VB2_FILEIO_WRITE_IMMEDIATELY = (1 << 1),
> + VB2_FILEIO_ALLOW_ZERO_BYTESUSED = (1 << 2),
> };
>
> /**
>
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