Re: [PATCH v3 1/3] media: rkvdec: Fix .buf_prepare

From: Nicolas Dufresne
Date: Thu May 14 2020 - 10:51:10 EST


Le mardi 05 mai 2020 Ã 10:41 -0300, Ezequiel Garcia a Ãcrit :
> The driver should only set the payload on .buf_prepare
> if the buffer is CAPTURE type, or if an OUTPUT buffer
> has a zeroed payload.
>
> Fix it.
>
> Fixes: cd33c830448ba ("media: rkvdec: Add the rkvdec driver")
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> ---
> 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 225eeca73356..4df2a248ab96 100644
> --- a/drivers/staging/media/rkvdec/rkvdec.c
> +++ b/drivers/staging/media/rkvdec/rkvdec.c
> @@ -456,7 +456,15 @@ 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's bytesused is written by the driver for CAPTURE buffers,
> + * or if the application passed zero bytesused on an OUTPUT buffer.
> + */
> + if (!V4L2_TYPE_IS_OUTPUT(vq->type) ||
> + (V4L2_TYPE_IS_OUTPUT(vq->type) && !vb2_get_plane_payload(vb, 0)))
> + vb2_set_plane_payload(vb, 0,
> + f->fmt.pix_mp.plane_fmt[0].sizeimage);

I believe the spec lacks a bit of a clarification. Converting from 0 to
sizeimage should only be allowed for RAW images. So I would like to suggest to
change this fix into:

- vb2_set_plane_payload(vb, 0, f->fmt.pix_mp.plane_fmt[0].sizeimage);
+
+ /* Buffer's bytesused is written by the driver for CAPTURE buffers */
+ if (!V4L2_TYPE_IS_OUTPUT(vq->type))
+ vb2_set_plane_payload(vb, 0,
+ f->fmt.pix_mp.plane_fmt[0].sizeimage);

And then we can fix the spec accordingly. Note that neighter FFMPEG or GStreamer
will pass empty (zero sized) payload at the moment, and if it did, it would be a
bug, and the payload should instead be ignored.

> return 0;
> }
>
> --
> 2.26.0.rc2
>
>