Re: [PATCH v3 17/27] drm/msm/mdss: use new helper to set amsbc

Dmitry Baryshkov
2026-03-16T14:04:52Z

On Mon, Mar 16, 2026 at 11:08:00AM +0100, Konrad Dybcio wrote:
> On 3/13/26 3:26 PM, Dmitry Baryshkov wrote:
> > On Fri, Mar 13, 2026 at 11:19:59AM +0100, Konrad Dybcio wrote:
> >> On 3/12/26 2:29 PM, Dmitry Baryshkov wrote:
> >>> Use freshly defined helper instead of checking the UBWC version
> >>> directly.
> >>>
> >>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> >>> ---
> >>> drivers/gpu/drm/msm/msm_mdss.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
> >>> index ca59bcdde7b2..04efc29f38cd 100644
> >>> --- a/drivers/gpu/drm/msm/msm_mdss.c
> >>> +++ b/drivers/gpu/drm/msm/msm_mdss.c
> >>> @@ -188,7 +188,7 @@ static void msm_mdss_5x_setup_ubwc(struct msm_mdss *msm_mdss)
> >>> if (qcom_ubwc_macrotile_mode(data))
> >>> value |= MDSS_UBWC_STATIC_MACROTILE_MODE;
> >>>
> >>> - if (data->ubwc_enc_version == UBWC_3_0)
> >>> + if (qcom_ubwc_enable_amsbc(data))
> >>> value |= MDSS_UBWC_STATIC_UBWC_AMSBC;
> >>
> >> I know it's already there, but fwiw downstream doesn't seem to be
> >> concerned with toggling AMSBC in MDSS (perhaps incorrectly?)
> >
> > Downstream enables it only for the cases where encoder and decoder
> > use exactly UBWC 3.0. This is not completely correct as the bit doesn't
> > exist for MDSS 6.x+. For 5.x this is equivalent to the code from the
> > patch: enable AMSBC if targeting UBWC >= 3.0 (because MDSS 5.x don't
> > support UBWC 4.0 or higher).
>
> Right, this seems to indeed be the case
>
> While trying to confirm that, I noticed that some lower-end MDSS 5.x
> chips (like Talos) report UBWC3 in the register, but the MDSS docs say
> they're UBWC2 - any idea?

I don't see a complete pixel format document for Talos, but my guess is
that one of the blocks (GPU, Venus or Camera) doesn't support UBWC 3.0
pixel formats. MDSS is just one piece of picture and unfortunately we
need to use format which is supported by all the blocks.

--
With best wishes
Dmitry