linux-kernel - Re: [PATCH] dt-bindings: arm-smmu: disallow clocks when not used

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Message-ID: <5025ab98-ecd2-2fa1-adbc-15b4fd6e85b3@linaro.org>
Date:   Thu, 22 Dec 2022 15:03:20 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: Re: [PATCH] dt-bindings: arm-smmu: disallow clocks when not used

On 22/12/2022 14:33, Marijn Suijten wrote:
> On 2022-12-22 11:36:16, Krzysztof Kozlowski wrote:
>> On 22/12/2022 11:16, Marijn Suijten wrote:
>>> Is this missing a cc to linux-arm-msm?
>>
>> No, it is not (or maybe but then fix MAINTAINERS). The policy is to use
>> get_maintainers.pl to CC people.
> 
> Yes, that is the question: is it in MANTAINERS and if not, why not?

You can check by yourself if it is there.

Why not? I don't know. Could be that no one ever added it there.

> 
>>> On 2022-12-22 10:23:55, Krzysztof Kozlowski wrote:
>>>> Disallow clocks for variants other than:
>>>> 1. SMMUs with platform-specific compatibles which list explicit clocks
>>>>    and clock-names,
>>>> 2. SMMUs using only generic compatibles, e.g. arm,mmu-500, which have a
>>>>    variable clocks on different implementations.
>>>>
>>>> This requires such variants with platform-specific compatible, to
>>>> explicitly list the clocks or omit them, making the binding more
>>>> constraint.
>>>>
>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>>>
>>> Reviewed-by: Marijn Suijten <marijn.suijten@...ainline.org>
>>>
>>> But...
>>>
>>>> ---
>>>>
>>>> Cc: Marijn Suijten <marijn.suijten@...ainline.org>
>>>> Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>> Cc: Konrad Dybcio <konrad.dybcio@...aro.org>
>>>> ---
>>>>  .../devicetree/bindings/iommu/arm,smmu.yaml   | 28 +++++++++++++++++++
>>>>  1 file changed, 28 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>> index 895ec8418465..0d88395e43ad 100644
>>>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>> @@ -367,6 +367,34 @@ allOf:
>>>>              - description: interface clock required to access smmu's registers
>>>>                  through the TCU's programming interface.
>>>>  
>>>> +  # Disallow clocks for all other platforms with specific compatibles
>>>> +  - if:
>>>> +      properties:
>>>> +        compatible:
>>>> +          contains:
>>>> +            enum:
>>>> +              - cavium,smmu-v2
>>>> +              - marvell,ap806-smmu-500
>>>> +              - nvidia,smmu-500
>>>> +              - qcom,qcm2290-smmu-500
>>>> +              - qcom,qdu1000-smmu-500
>>>> +              - qcom,sc7180-smmu-500
>>>
>>> Hmm, sc7280 has two SMMUs.  The one for Adreno has clocks and a PD, the
>>
>> sc7280 is not here, so what is the mistake you see?
> 
> sc7280 has two IOMMU nodes.  One with clocks (should not be in this
> list), the other doesn't have clocks (should be in this list).
> 
> How do you want to address that?

No, because it is the same compatible.

Best regards,
Krzysztof