Re: [PATCH 1/5] dt-bindings: arm: mediatek: mmsys: change compatible for MT8195

[Matthias Brugger]

Hi Jason,

On 15/09/2022 03:24, Jason-JH Lin wrote:
> Hi Matthias,
>
> Thanks for the reviews.
>
> On Wed, 2022-09-14 at 23:24 +0200, Matthias Brugger wrote:
> > On 14/09/2022 20:23, Jason-JH.Lin wrote:
> > > For previous MediaTek SoCs, such as MT8173, there are 2 display HW
> > > pipelines binding to 1 mmsys with the same power domain, the same
> > > clock driver and the same mediatek-drm driver.
> > >
> > > For MT8195, VDOSYS0 and VDOSYS1 are 2 display HW pipelines binding
> > > to
> > > 2 different power domains, different clock drivers and different
> > > mediatek-drm drivers.
> > >
> > > Moreover, Hardware pipeline of VDOSYS0 has these components: COLOR,
> > > CCORR, AAL, GAMMA, DITHER. They are related to the PQ (Picture
> > > Quality)
> > > and they makes VDOSYS0 supports PQ function while they are not
> > > including in VDOSYS1.
> > >
> > > Hardware pipeline of VDOSYS1 has the component ETHDR (HDR related
> > > component). It makes VDOSYS1 supports the HDR function while it's
> > > not
> > > including in VDOSYS0.
> > >
> > > To summarize0:
> > > Only VDOSYS0 can support PQ adjustment.
> > > Only VDOSYS1 can support HDR adjustment.
> > >
> > > Therefore, we need to separate these two different mmsys hardwares
> > > to
> > > 2 different compatibles for MT8195.
> > >
> > > Fixes: 81c5a41d10b9 ("dt-bindings: arm: mediatek: mmsys: add mt8195
> > > SoC binding")
> > > Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
> > > Signed-off-by: Bo-Chen Chen <rex-bc.chen@xxxxxxxxxxxx>
> > > Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> >
> > I'm not sure Krzysztof gave his Acked-by tag.
>
> I'll remove this tag.
> > > ---
> > >    .../devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml        |
> > > 2 ++
> > >    1 file changed, 2 insertions(+)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
> > > l
> > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
> > > l
> > > index 6ad023eec193..a53b32c0a608 100644
> > > ---
> > > a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
> > > l
> > > +++
> > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
> > > l
> > > @@ -32,6 +32,8 @@ properties:
> > >                  - mediatek,mt8186-mmsys
> > >                  - mediatek,mt8192-mmsys
> > >                  - mediatek,mt8195-mmsys
> > > +              - mediatek,mt8195-vdosys0
> >
> > As I said in the last submission, we should make mediatek,mt8195-
> > mmsys as a
> > fallback of vdosys0. Actually mediatek,mt8195-mmsys is only used for
> > the
> > fallback of vdosys0.
>
> I think adding both vdosys0 and vdosys1 can make the description of
> this patch clearer.
>
> It's find to me to only add "mediatek,mt8195-vdosys0" in this patch.
> So I'll remove the "mediatek,mt8195-vdosys1" at the next version.

That's not what I wanted to suggest. Up to now in upstream kernel compatible 
mediatek,mt8195-mmsys enables support fro vdosys0. The vdosys1 is not yet 
upstream, so no support.
If we change the compatible, we should keep mediatek,mt8195-mmsys as fallback of 
"mediatek,mt8195-vdosys0" so that older device tree blobs won't break with a 
newer kernel.
For "mediatek,mt8195-vdosys1" we do not need a fallback compatible as the code 
never reached upstream, so no breakage expected.

Hope I explain myself now.

Regards,
Matthias


> Regards,
> Jason-JH.Lin
> > Regards,
> > Matthias
> >
> > > +              - mediatek,mt8195-vdosys1
> > >                  - mediatek,mt8365-mmsys
> > >              - const: syscon
> > >          - items: