Le jeudi 05 novembre 2026 à 13:35 +0100, Robert Mader a écrit :
> On 04.11.26 23:11, Rob Clark wrote:
> > On Wed, Nov 4, 2026 at 11:00 AM Robert Mader <robert.mader@collabora.com> wrote:
> > > Nice, very happy to see the series!
> > > 
> > > On 04.11.26 17:36, Dmitry Baryshkov wrote:
> > > > The comment describing the QC10C buffer layout calls it a compressed
> > > > P010. It is not:
> > > If I'm not mistaken the display engine / the DRM side (including Mesa)
> > > describes it as P010+QCOM_COMPRESSED as well, and so does my pending
> > > Gstreamer MR [1] . So if we can't pretend that QC10C ==
> > > P010+QCOM_COMPRESSED, then we probably need a DRM_FORMAT_TP10, wire that
> > > up everywhere etc. OTOH if we want to keep the DRM side as is, then the
> > > comment should reflect that, IMO.
> > IMHO we need DRM_FORMAT_TP10.. on the GPU side, we have TP10 and P010
> > as distinct formats, both with and without UBWC.  I'm not sure if the
> > same is true on video side but P010+UBWC was never exposed, or if it
> > truely only supports linear P010 and UBWC TP10.
> 
> Oh, do I understand you correctly that the P010+UBWC implementation is 
> not compatible with QC10C, meaning on the GPU side (Mesa and display) we 
> don't yet have any support for QC10C exposed to userspace? If that's so 
> then we don't have a choice but to introduce DRM_FORMAT_TP10 I guess?
> 
> On the plus side - this would allow us to make the format single plane, 
> matching what we get on the V4L2 side.

Since its single plane, we should aim for a variation of
DRM_FORMAT_YUV420_10BIT. Similar to YUV420_10BIT, there is no obvious linear
single plane packing for that, it would only be there to support the
compression. Or maybe this one is abstract enough to be used anyway?

Nicolas

> 
> > 
> > BR,
> > -R
> > 
> > > Best regards,
> > > 
> > > Robert
> > > 
> > > 1: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8195
> > > 
> > > > P010 stores each sample in 16 bits, QC10C packs three
> > > > 10-bit samples in each 32-bit word, which is what the stride computed
> > > > below (width * 4 / 3) assumes. Name the format correctly.
> > > > 
> > > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> > > > ---
> > > >    drivers/media/platform/qcom/iris/iris_buffer.c | 2 +-
> > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/media/platform/qcom/iris/iris_buffer.c b/drivers/media/platform/qcom/iris/iris_buffer.c
> > > > index eb8de60c1177..ec2bf2a2d953 100644
> > > > --- a/drivers/media/platform/qcom/iris/iris_buffer.c
> > > > +++ b/drivers/media/platform/qcom/iris/iris_buffer.c
> > > > @@ -266,7 +266,7 @@ static u32 iris_yuv_buffer_size_qc08c(struct iris_inst *inst)
> > > > 
> > > >    /*
> > > >     * QC10C:
> > > > - * UBWC-compressed format for P010.
> > > > + * UBWC-compressed TP10, YUV 4:2:0 with three 10 bit samples packed in 32 bits.
> > > >     * Contains 4 planes in the following order -
> > > >     * (A) Y_Meta_Plane
> > > >     * (B) Y_UBWC_Plane
> > > >