Re: [PATCH 2/2] media: venus: venc: fix bytesused v4l2_plane field

[Stanimir Varbanov]

Hans,

On  9.10.2017 15:31, Hans Verkuil wrote:
> On 09/10/17 14:24, Stanimir Varbanov wrote:
> > This fixes wrongly filled bytesused field of v4l2_plane structure
> > by include data_offset in the plane, Also fill data_offset and
> > bytesused for capture type of buffers only.
> >
> > Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx>
> > ---
> >   drivers/media/platform/qcom/venus/venc.c | 9 +++++----
> >   1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c
> > index 6f123a387cf9..9445ad492966 100644
> > --- a/drivers/media/platform/qcom/venus/venc.c
> > +++ b/drivers/media/platform/qcom/venus/venc.c
> > @@ -963,15 +963,16 @@ static void venc_buf_done(struct venus_inst *inst, unsigned int buf_type,
> >   	if (!vbuf)
> >   		return;
> >   
> > -	vb = &vbuf->vb2_buf;
> > -	vb->planes[0].bytesused = bytesused;
> > -	vb->planes[0].data_offset = data_offset;
> > -
> >   	vbuf->flags = flags;
> >   
> >   	if (type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
> > +		vb = &vbuf->vb2_buf;
> > +		vb2_set_plane_payload(vb, 0, bytesused + data_offset);
> > +		vb->planes[0].data_offset = data_offset;
> >   		vb->timestamp = timestamp_us * NSEC_PER_USEC;
> >   		vbuf->sequence = inst->sequence_cap++;
> > +
> > +		WARN_ON(vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0));
>
> It's good to have this, but this really should never happen. Because if it is,
> then you'll have a memory overwrite. I hope the DMA engine will prevent this? >
> Just wondering how this works.
>
> The patch looks good otherwise, but that WARN_ON is a bit scary.

Infact it is not so scary as it looks like, the IOMMU will catch this 
and generate a fault. So most probably we will never come to the WARN, 
thus the warning is pointless so will delete it.

regards,
Stan