[PATCH] media: rkvdec: Fix .buf_prepare

[Ezequiel Garcia]

Hi Andrzej,

Thanks a lot for picking this up.

On Tue, 2021-05-04 at 13:37 +0200, Andrzej Pietrasiewicz wrote:
> From: Ezequiel Garcia <ezequiel at collabora.com>
> 
> The driver should only set the payload on .buf_prepare if the
> buffer is CAPTURE type. If an OUTPUT buffer has a zero bytesused
> set by userspace then v4l2-core will set it to buffer length.
> 
> Fixes: cd33c830448ba ("media: rkvdec: Add the rkvdec driver")
> Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
> Signed-off-by: Adrian Ratiu <adrian.ratiu at collabora.com>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at collabora.com>
> 
> ---
> @Hans: I haven't had anyone complain about the issue. The fix is needed for
> the rkvdec vp9 work, so I think 5.14 is fine.
> 
>  drivers/staging/media/rkvdec/rkvdec.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/media/rkvdec/rkvdec.c b/drivers/staging/media/rkvdec/rkvdec.c
> index d821661d30f3..ef2166043127 100644
> --- a/drivers/staging/media/rkvdec/rkvdec.c
> +++ b/drivers/staging/media/rkvdec/rkvdec.c
> @@ -481,7 +481,15 @@ static int rkvdec_buf_prepare(struct vb2_buffer *vb)
>                 if (vb2_plane_size(vb, i) < sizeimage)
>                         return -EINVAL;
>         }
> -       vb2_set_plane_payload(vb, 0, f->fmt.pix_mp.plane_fmt[0].sizeimage);
> +
> +       /*
> +        * Buffer bytesused is written by driver for CAPTURE buffers.
> +        * (if userspace passes 0 bytesused for OUTPUT buffers, v4l2-core sets
> +        * it to buffer length).
> +        */
> +       if (!V4L2_TYPE_IS_OUTPUT(vq->type))

Please use V4L2_TYPE_IS_CAPTURE here.

Also, why is this change needed in rkvdec, but not in cedrus
or hantro?

Thanks!
Ezequiel