linux-kernel - Re: [PATCH v3 1/6] dt-bindings: arm: mediatek: mmsys: change compatible for MT8195

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Message-ID: <29a06da0-ddf5-15eb-ac3d-0bc2e0006ae9@linaro.org>
Date:   Wed, 21 Sep 2022 08:28:34 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Jason-JH Lin <jason-jh.lin@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     CK Hu <ck.hu@...iatek.com>, Rex-BC Chen <rex-bc.chen@...iatek.com>,
        Singo Chang <singo.chang@...iatek.com>,
        Nancy Lin <nancy.lin@...iatek.com>,
        dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v3 1/6] dt-bindings: arm: mediatek: mmsys: change
 compatible for MT8195

On 21/09/2022 06:16, Jason-JH Lin wrote:
> Hi Krzysztof,
> 
> Thanks for the reviews.
> 
> On Tue, 2022-09-20 at 17:25 +0200, Krzysztof Kozlowski wrote:
>> On 20/09/2022 16:01, 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@...iatek.com>
>>> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
>>> ---
>>>  .../devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml      | 4
>>> ++++
>>>  1 file changed, 4 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..df9184b6772c 100644
>>> ---
>>> a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
>>> l
>>> +++
>>> b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yam
>>> l
>>> @@ -38,6 +38,10 @@ properties:
>>>            - const: mediatek,mt7623-mmsys
>>>            - const: mediatek,mt2701-mmsys
>>>            - const: syscon
>>> +      - items:
>>> +          - const: mediatek,mt8195-vdosys0
>>> +          - const: mediatek,mt8195-mmsys
>>> +          - const: syscon
>>
>> and why mediatek,mt8195-mmsys is kept as non-deprecated?
> 
> Shouldn't we keep this for fallback compatible?

I am not talking about it.

> 
> I think this items could support the device node like:
> foo {
>   compatible = "mediatek,mt8195-vdosys0", "mediatek,mt8195-mmsys", 
> 	       "syscon";
> }
> 

Yes, this one ok.

> 
> Or should I change the items like this?
> - items:
>     - const: mediatek,mt8195-vdosys0
>     - enum:
>         - mediatek,mt8195-mmsys
>     - const: syscon
> 

No, this does not look correct.

I asked why do you keep old mediatek,mt8195-mmsys compatible in the same
place (the alone one), without making it deprecated?

Best regards,
Krzysztof