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Date:   Wed, 2 Nov 2022 20:44:12 -0700
From:   Bjorn Andersson <quic_bjorande@quicinc.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
CC:     Georgi Djakov <djakov@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        "Sibi Sankar" <quic_sibis@quicinc.com>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Mike Tipton <quic_mdtipton@quicinc.com>,
        Johan Hovold <johan+linaro@kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-pm@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 05/10] dt-bindings: interconnect: Add sm8350, sc8280xp
 and generic OSM L3 compatibles
Message-ID: <20221103034410.GB5525@core-thresher1.qualcomm.com>
References: <20221028034155.5580-1-quic_bjorande@quicinc.com>
 <20221028034155.5580-6-quic_bjorande@quicinc.com>
 <a364b343-fa19-348c-bc38-e8b44061890b@linaro.org>
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On Fri, Oct 28, 2022 at 06:12:29PM -0400, Krzysztof Kozlowski wrote:
> On 27/10/2022 23:41, Bjorn Andersson wrote:
> > Add EPSS L3 compatibles for sm8350 and sc8280xp, but while at it also
> > introduce generic compatible for both qcom,osm-l3 and qcom,epss-l3.
> > 
> > Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
> > ---
> >  .../bindings/interconnect/qcom,osm-l3.yaml    | 22 +++++++++++++------
> >  1 file changed, 15 insertions(+), 7 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml b/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
> > index bf538c0c5a81..ae0995341a78 100644
> > --- a/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
> > +++ b/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
> > @@ -16,13 +16,21 @@ description:
> >  
> >  properties:
> >    compatible:
> > -    enum:
> > -      - qcom,sc7180-osm-l3
> > -      - qcom,sc7280-epss-l3
> > -      - qcom,sc8180x-osm-l3
> > -      - qcom,sdm845-osm-l3
> > -      - qcom,sm8150-osm-l3
> > -      - qcom,sm8250-epss-l3
> > +    oneOf:
> > +      items:
> 
> oneOf expects a list, so this should be "    - items"
> 

Ahh, thanks. Must have missed running the dt_binding_check on this one.

> > +        - enum:
> > +            - qcom,sc7180-osm-l3
> > +            - qcom,sc8180x-osm-l3
> > +            - qcom,sdm845-osm-l3
> > +            - qcom,sm8150-osm-l3
> > +        - const: qcom,osm-l3
> 
> The concept is good, but are you sure all SoCs will be compatible with
> generic osm-l3?

Per the current implementation yes, worst case if one or more of them isn't the
more specific compatible can be used to alter the behavior of that platform.

> Why not using dedicated compatible of one soc, e.g. the
> oldest here? We already did like that for BWMON, DMA and few others.
> 

Because if we say compatible = "qcom,sc8180x-osm-l3", "qcom,sdm845-osm-l3" and
there is a quirk needed for "qcom,sdm845-osm-l3" we're forced to add a "special
case" every other *-osm-l3 in the driver.

This way we can have a generic implementation for the qcom,osm-l3 and if we
realize that we need to quirk something for the oldest platform, we can do so
without affecting the others.

Regards,
Bjorn

> > +      items:
> > +        - enum:
> > +            - qcom,sc7280-epss-l3
> > +            - qcom,sc8280xp-epss-l3
> > +            - qcom,sm8250-epss-l3
> > +            - qcom,sm8350-epss-l3
> > +        - const: qcom,epss-l3
> >  
> >    reg:
> >      maxItems: 1
> 
> Best regards,
> Krzysztof
>