Date:   Wed, 14 Sep 2022 23:09:56 +0800
From:   Jason-JH Lin <jason-jh.lin@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        Bo-Chen Chen <rex-bc.chen@...iatek.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>
CC:     Nancy Lin (林欣螢) 
        <Nancy.Lin@...iatek.com>,
        CK Hu (胡俊光) 
        <ck.hu@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "hsinyi@...gle.com" <hsinyi@...gle.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v2] dt-bindings: arm: mediatek: mmsys: change compatible
 for MT8195


On Wed, 2022-09-14 at 16:32 +0200, Matthias Brugger wrote:
> 
> On 26/08/2022 17:39, Matthias Brugger wrote:
> > 
> > 
> > On 26/08/2022 09:13, Bo-Chen Chen wrote:
> > > On Fri, 2022-08-26 at 15:00 +0800, Krzysztof Kozlowski wrote:
> > > > On 26/08/2022 05:07, Bo-Chen Chen wrote:
> > > > > On Thu, 2022-08-25 at 22:57 +0800, Matthias Brugger wrote:
> > > > > > 
> > > > > > On 25/08/2022 11:14, Bo-Chen Chen wrote:
> > > > > > > From: "Jason-JH.Lin" <jason-jh.lin@...iatek.com>
> > > > > > > 
> > > > > > > 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>
> > > > > > > ---
> > > > > > > Changes for v2:
> > > > > > > 1. Add hardware difference for VDOSYS0 and VDOSYS1 in
> > > > > > > commit
> > > > > > > message.
> > > > > > > ---
> > > > > > > .../devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
> > > > > > > > 
> > > > > > > 
> > > > > > > 3 ++-
> > > > > > >    1 file changed, 2 insertions(+), 1 deletion(-)
> > > > > > > 
> > > > > > > diff --git
> > > > > > > a/Documentation/devicetree/bindings/arm/mediatek/mediatek
> > > > > > > ,mmsys
> > > > > > > .yam
> > > > > > > l
> > > > > > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek
> > > > > > > ,mmsys
> > > > > > > .yam
> > > > > > > l
> > > > > > > index 6ad023eec193..bfbdd30d2092 100644
> > > > > > > ---
> > > > > > > a/Documentation/devicetree/bindings/arm/mediatek/mediatek
> > > > > > > ,mmsys
> > > > > > > .yam
> > > > > > > l
> > > > > > > +++
> > > > > > > b/Documentation/devicetree/bindings/arm/mediatek/mediatek
> > > > > > > ,mmsys
> > > > > > > .yam
> > > > > > > l
> > > > > > > @@ -31,7 +31,8 @@ properties:
> > > > > > >                  - mediatek,mt8183-mmsys
> > > > > > >                  - mediatek,mt8186-mmsys
> > > > > > >                  - mediatek,mt8192-mmsys
> > > > > > > -              - mediatek,mt8195-mmsys
> > > > > > > +              - mediatek,mt8195-vdosys0
> > > > > > 
> > > > > > Thanks for you patch. As I mentioned on v1, I propose to
> > > > > > set
> > > > > > mediatek,mt8195-mmsys as fallback for mediatek,mt8195-
> > > > > > vdosys0 to
> > > > > > not
> > > > > > break
> > > > > > backwards compatibility.
> > > > > > 
> > > > > > Apart from that, the binding change will need some changes
> > > > > > to
> > > > > > support
> > > > > > the new
> > > > > > binding. Please provide these together with this patch.
> > > > > > 
> > > > > > Regards,
> > > > > > Matthias
> > > > > > 
> > > > > 
> > > > > Hello Matthias,
> > > > > 
> > > > > Thanks for your comments.
> > > > > The purpose of this patch is to confirm we can separate
> > > > > mt8195
> > > > > mmsys
> > > > > into two compatibles. I think this modification is accepted.
> > > > 
> > > > No, it is not accepted following Matthias comments. You
> > > > received my
> > > > ack
> > > > based on assumption that ABI break is perfectly ok for platform
> > > > maintainer, as he has decisive voice. If anyone is not happy
> > > > with a
> > > > ABI
> > > > break, then his concerns must be addressed.
> > > > 
> > > > So let it be specific:
> > > > NAK.
> > > > 
> > > > > 
> > > > > After this, I think Jason-JH will push another series with
> > > > > this
> > > > > binding
> > > > > patch.
> > > > 
> > > > I don't know what do you mean here - another series on top of
> > > > wrong
> > > > patch?
> > > > 
> > > 
> > > Hello Krzysztof,
> > > 
> > > For this mt8195 mmsys binding separation, we still need to modify
> > > driver for this. The reason I send this patch is to confirm we
> > > can do
> > > this binding modification and I also think we can not pick this
> > > patch
> > > here.
> > > 
> > > We will push another series and it contains modification of
> > > binding and
> > > drivers. (The series will push by Jason-JH Lin)
> > > 
> > 
> > Sounds good. So lets wait for Jason-JH Lin to send this series and
> > we can go on 
> > with the review.
> > 
> 
> Just to be sure, this has not happened yet, correct?
> 
> Regards,
> Matthias

Yes, sorry for the late reply to you.
I'll start to send this series at 9/19.

Regards,
Jason-JH.Lin

> 
> > Thanks!
> > Matthias
> > 
> > > Maybe I should use "RFC" for this series, and I think it's more
> > > correct.
> > > 
> > > BRs,
> > > Bo-Chen
> > > 
> > > > > In Jason-JH's series, we will modify mmsys driver based on
> > > > > this.
> > > > > And I think we don't need to keep "mediatek,mt8195-mmsys" if
> > > > > we
> > > > > also
> > > > > modify mmsys drivers in the same series.
> > > > 
> > > > This does not fux ABI break and broken bisectability.
> > > > 
> > > > > 
> > > > > Is it ok that postpones to pick this patch until we finish
> > > > > review
> > > > > follow-up series?
> > > > > 
> > > > 
> > > > No. You got a clear review to fix.
> > > > 
> > > > Best regards,
> > > > Krzysztof
-- 
Jason-JH Lin <jason-jh.lin@...iatek.com>

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