linux-kernel - RE: [Patch v4 01/11] dt-bindings: media: s5p-mfc: Add mfcv12 variant

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Date:   Wed, 8 Nov 2023 22:54:55 +0530
From:   "Alim Akhtar" <alim.akhtar@...sung.com>
To:     "'Krzysztof Kozlowski'" <krzysztof.kozlowski@...aro.org>,
        "'Aakarsh Jain'" <aakarsh.jain@...sung.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Cc:     <m.szyprowski@...sung.com>, <andrzej.hajda@...el.com>,
        <mchehab@...nel.org>, <hverkuil-cisco@...all.nl>,
        <krzysztof.kozlowski+dt@...aro.org>, <dillon.minfei@...il.com>,
        <david.plowman@...pberrypi.com>, <mark.rutland@....com>,
        <robh+dt@...nel.org>, <conor+dt@...nel.org>,
        <linux-samsung-soc@...r.kernel.org>, <andi@...zian.org>,
        <gost.dev@...sung.com>, <aswani.reddy@...sung.com>,
        <pankaj.dubey@...sung.com>, <ajaykumar.rs@...sung.com>,
        <linux-fsd@...la.com>
Subject: RE: [Patch v4 01/11] dt-bindings: media: s5p-mfc: Add mfcv12
 variant

Hi Aakarsh

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Sent: Wednesday, November 1, 2023 1:54 PM
> To: Aakarsh Jain <aakarsh.jain@...sung.com>; linux-arm-
> kernel@...ts.infradead.org; linux-media@...r.kernel.org; linux-
> kernel@...r.kernel.org; devicetree@...r.kernel.org
> Cc: m.szyprowski@...sung.com; andrzej.hajda@...el.com;
> mchehab@...nel.org; hverkuil-cisco@...all.nl;
> krzysztof.kozlowski+dt@...aro.org; dillon.minfei@...il.com;
> david.plowman@...pberrypi.com; mark.rutland@....com;
> robh+dt@...nel.org; conor+dt@...nel.org; linux-samsung-
> soc@...r.kernel.org; andi@...zian.org; gost.dev@...sung.com;
> alim.akhtar@...sung.com; aswani.reddy@...sung.com;
> pankaj.dubey@...sung.com; ajaykumar.rs@...sung.com; linux-
> fsd@...la.com
> Subject: Re: [Patch v4 01/11] dt-bindings: media: s5p-mfc: Add mfcv12
> variant
> 
> On 26/10/2023 15:31, Aakarsh Jain wrote:
> > Hello Krzysztof
> >
> >> -----Original Message-----
> >> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >> Sent: 25 October 2023 18:30
> >> To: Aakarsh Jain <aakarsh.jain@...sung.com>; linux-arm-
> >> kernel@...ts.infradead.org; linux-media@...r.kernel.org; linux-
> >> kernel@...r.kernel.org; devicetree@...r.kernel.org
> >> Cc: m.szyprowski@...sung.com; andrzej.hajda@...el.com;
> >> mchehab@...nel.org; hverkuil-cisco@...all.nl;
> >> krzysztof.kozlowski+dt@...aro.org; dillon.minfei@...il.com;
> >> david.plowman@...pberrypi.com; mark.rutland@....com;
> >> robh+dt@...nel.org; conor+dt@...nel.org; linux-samsung-
> >> soc@...r.kernel.org; andi@...zian.org; gost.dev@...sung.com;
> >> alim.akhtar@...sung.com; aswani.reddy@...sung.com;
> >> pankaj.dubey@...sung.com; ajaykumar.rs@...sung.com; linux-
> >> fsd@...la.com
> >> Subject: Re: [Patch v4 01/11] dt-bindings: media: s5p-mfc: Add mfcv12
> >> variant
> >>
> >> On 25/10/2023 12:22, Aakarsh Jain wrote:
> >>> Add Tesla FSD MFC(MFC v12) compatible.
> >>>
> >>> Cc: linux-fsd@...la.com
> >>> Signed-off-by: Aakarsh Jain <aakarsh.jain@...sung.com>
> >>> ---
> >>
> >> No changelog and your cover letter does not explain what happened
> here.
> >> Specifically, why did you decide to ignore received tag.
> >>
> > Last patch series we had two different patches for schema which was one
> for adding MFCv12 compatible string and other for adding its HW properties.
> > In one of the patches you gave reviewed-by tag. Since mfc dt_schema got
> merged already, and this is relatively  new patch so thought of getting
> reviewed again.
> >
> > Link to those patches:
> > https://patchwork.kernel.org/project/linux-
> media/patch/20221011122516.32135-2-aakarsh.jain@...sung.com/
> > https://patchwork.kernel.org/project/linux-
> media/patch/20221011122516.32135-3-aakarsh.jain@...sung.com/
> >
> > if you are ok, I will add your reviewed-by in next patch series.
> 
> It is okay to drop Reviewed-by tag, but this should be explicitly mentioned in
> the changelog with a reason.
> 
> >
> >>>  .../bindings/media/samsung,s5p-mfc.yaml          | 16
> ++++++++++++++++
> >>>  1 file changed, 16 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/media/samsung,s5p-
> >> mfc.yaml b/Documentation/devicetree/bindings/media/samsung,s5p-
> >> mfc.yaml
> >>> index 084b44582a43..c30eb309f670 100644
> >>> --- a/Documentation/devicetree/bindings/media/samsung,s5p-
> mfc.yaml
> >>> +++ b/Documentation/devicetree/bindings/media/samsung,s5p-
> mfc.yaml
> >>> @@ -24,6 +24,7 @@ properties:
> >>>            - samsung,mfc-v7                # Exynos5420
> >>>            - samsung,mfc-v8                # Exynos5800
> >>>            - samsung,mfc-v10               # Exynos7880
> >>> +          - tesla,fsd-mfc                 # Tesla FSD
> >>>        - items:
> >>>            - enum:
> >>>                - samsung,exynos3250-mfc    # Exynos3250
> >>> @@ -165,6 +166,21 @@ allOf:
> >>>            minItems: 1
> >>>            maxItems: 2
> >>>
> >>> +  - if:
> >>> +      properties:
> >>> +        compatible:
> >>> +          contains:
> >>> +            enum:
> >>> +              - tesla,fsd-mfc
> >>> +    then:
> >>> +      properties:
> >>> +        clocks:
> >>> +          maxItems: 1
> >>> +        clock-names:
> >>> +          items:
> >>> +            - const: mfc
> >>> +        iommus: false
> >>
> >> That's odd. How so? MFC v12 does not support IOMMU?
> >>
> > MFC v12 do support IOMMU. But currently it is not enabled in SW (has
> dependencies on some of the floating dma-mapping patches) and not tested
> on upstream kernel.
> 
> Bindings describe hardware, not software.
> 
> > Current patch sets intend to add support for MFCv12 using reserve
> memory and later patches related to enable iommu will be posted (after
> resolving the dependencies). So I marked iommu property as false.
> > Now what is your suggestion here? Should I keep iommu as false or add
> memory-region as below?
> 
> I expect complete picture of the hardware, not something limited to current
> driver, so for sure iommus must be there.
> 
As Krzysztof mentioned, DT binding should explain all the hardware features supported by SoC / IPs. 
Incase a feature is not enabled for some reason, that need to be handled in the dts file.

> Please wrap your emails according to mailing lists rules.
> 
> Best regards,
> Krzysztof