Hi Michael,
On Fri, May 06, 2022 at 11:58:21AM +0200, Michael Rodin wrote:
> Hi Laurent,
>
> do you see any open points for this patch? If not, do you know maybe when
> it will be available on linux-media or maybe mainline branch?
I've just sent a pull request that includes this fix, I hope it will
make it to v5.19.
> On Tue, Apr 19, 2022 at 12:22:15PM +0200, Michael Rodin wrote:
> > On Thu, Apr 14, 2022 at 05:20:14PM +0300, Laurent Pinchart wrote:
> > > Hi Michael,
> > >
> > > Your previous mail slipped through the cracks, sorry about that.
> > >
> > > On Wed, Mar 02, 2022 at 12:00:12PM +0100, Michael Rodin wrote:
> > > > Hi Laurent,
> > > >
> > > > thank you for your work!
> > > >
> > > > On Mon, Feb 28, 2022 at 02:00:58PM +0200, Laurent Pinchart wrote:
> > > > > From: Michael Rodin <mrodin@xxxxxxxxxxxxxx>
> > > > >
> > > > > The vertical subsampling factor is currently not considered in the
> > > > > offset calculation for plane cropping done in rpf_configure_partition.
> > > > > This causes a distortion (shift of the color plane) when formats with
> > > > > the vsub factor larger than 1 are used (e.g. NV12, see
> > > > > vsp1_video_formats in vsp1_pipe.c). This commit considers vsub factor
> > > > > for all planes except plane 0 (luminance).
> > > > >
> > > > > Fixes: e5ad37b64de9 ("[media] v4l: vsp1: Add cropping support")
> > > > > Signed-off-by: Michael Rodin <mrodin@xxxxxxxxxxxxxx>
> > > > > Signed-off-by: LUU HOAI <hoai.luu.ub@xxxxxxxxxxx>
> > > > >
> > > > > Drop generalization of the offset calculation to reduce the binary size.
> > > >
> > > > Dropping generalization which I have done in my initial patch [1] is ok as
> > > > long as this will not cause any troubles. I am not aware of any case where
> > > > bytesperline and bpp could be different between the chroma planes, so
> > > > probably it's fine.
> > > >
> > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> > > > > ---
> > > > > drivers/media/platform/vsp1/vsp1_rpf.c | 6 +++---
> > > > > 1 file changed, 3 insertions(+), 3 deletions(-)
> > > > >
> > > > > diff --git a/drivers/media/platform/vsp1/vsp1_rpf.c b/drivers/media/platform/vsp1/vsp1_rpf.c
> > > > > index 85587c1b6a37..75083cb234fe 100644
> > > > > --- a/drivers/media/platform/vsp1/vsp1_rpf.c
> > > > > +++ b/drivers/media/platform/vsp1/vsp1_rpf.c
> > > > > @@ -291,11 +291,11 @@ static void rpf_configure_partition(struct vsp1_entity *entity,
> > > > > + crop.left * fmtinfo->bpp[0] / 8;
> > > > >
> > > > > if (format->num_planes > 1) {
> > > > > + unsigned int bpl = format->plane_fmt[1].bytesperline;
> > > > > unsigned int offset;
> > > > >
> > > > > - offset = crop.top * format->plane_fmt[1].bytesperline
> > > > > - + crop.left / fmtinfo->hsub
> > > > > - * fmtinfo->bpp[1] / 8;
> > > > > + offset = crop.top / fmtinfo->vsub * bpl
> > > > > + + crop.left / fmtinfo->hsub * fmtinfo->bpp[1] / 8;
> > > >
> > > > Probably it makes sense to do the division after all multiplications are
> > > > done in order to avoid rounding errors? Consider the case when left = 3,
> > > > hsub = 2, bpp = 32. Then we would get for the second part of the offset:
> > > > 3 / 2 * 32 / 8 = 1 * 32 / 8 = 4
> > > > and if we do division as the last operation:
> > > > (3 * 32) / (8 * 2) = 96 / 16 = 6
> > >
> > > This was actually done on purpose :-) If the horizontal subsampling
> > > factor is equal to 2, for instance for the NV12 chroma plane, the
> > > horizontal offset must effectively be a multiple of 2. Otherwise you'll
> > > swap the Cr and Cb components.
> > >
> > > Taking your above example with a NV12 format (left=3, hsub=2, but
> > > bpp=16), with the rounding in this patch,
> > >
> > > offset = crop.top / fmtinfo->vsub * bpl
> > > + crop.left / fmtinfo->hsub * fmtinfo->bpp[1] / 8;
> > > = [vertical offset]
> > > + 3 / 2 * 16 / 8;
> > > = [vertical offset]
> > > + 2;
> > >
> > > Byte: 0 1 2 3 4 5
> > > Cr Cb Cr Cb Cr Cb ...
> > > ^
> > > offset
> > >
> > > With your rounding proposal,
> > >
> > > offset = crop.top / fmtinfo->vsub * bpl
> > > + (crop.left * fmtinfo->bpp[1]) / (fmtinfo->hsub * 8);
> > > = [vertical offset]
> > > + (3 * 16) / (2 * 8);
> > > = [vertical offset]
> > > + 3;
> > >
> > > Byte: 0 1 2 3 4 5
> > > Cr Cb Cr Cb Cr Cb ...
> > > ^
> > > offset
> >
> > Thank you very much for the clarification, I have missed this point!
> > Now the patch looks fine to me.
> >
> > Reviewed-by: Michael Rodin <mrodin@xxxxxxxxxxxxxx>
> >
> > > > The first part of the offset can probably also cause the same rounding
> > > > issue.
> > > >
> > > > > mem.addr[1] += offset;
> > > > > mem.addr[2] += offset;
> > > > > }
> > > > >
> > > >
> > > > [1] https://lore.kernel.org/all/1637679566-2D76975-1-git-send-email-mrodin-40de.adit-jv.com/T/
--
Regards,
Laurent Pinchart
