linux-kernel - Re: [PATCH v2 1/9] dt-bindings: arm-smmu: Allow up to 3 power-domains

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Message-ID: <4b4ca3ba-8e4d-088e-8b3e-a47ad6ecb965@linaro.org>
Date:   Tue, 15 Nov 2022 14:00:50 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org
Cc:     patches@...aro.org, 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
Subject: Re: [PATCH v2 1/9] dt-bindings: arm-smmu: Allow up to 3 power-domains

On 15/11/2022 13:54, Konrad Dybcio wrote:
> 
> 
> On 14/11/2022 17:58, Krzysztof Kozlowski wrote:
>> On 14/11/2022 16:53, Konrad Dybcio wrote:
>>>
>>> On 14/11/2022 14:00, Krzysztof Kozlowski wrote:
>>>> On 14/11/2022 12:17, Konrad Dybcio wrote:
>>>>> On 14/11/2022 12:01, Krzysztof Kozlowski wrote:
>>>>>> On 14/11/2022 11:42, Konrad Dybcio wrote:
>>>>>>> Some SMMUs require that a vote is held on as much as 3 separate PDs
>>>>>>> (hello Qualcomm). Allow it in bindings.
>>>>>>>
>>>>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>>>>>>> ---
>>>>>>> Changes since v1:
>>>>>>> - Add minItems
>>>>>>>
>>>>>>>     Documentation/devicetree/bindings/iommu/arm,smmu.yaml | 3 ++-
>>>>>>>     1 file changed, 2 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>>>>> index 9066e6df1ba1..82bc696de662 100644
>>>>>>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>>>>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
>>>>>>> @@ -159,7 +159,8 @@ properties:
>>>>>>>               through the TCU's programming interface.
>>>>>>>     
>>>>>>>       power-domains:
>>>>>>> -    maxItems: 1
>>>>>>> +    minItems: 0
>>>>>> It cannot be 0.
>>>>>>
>>>>>> minItems: 1
>>>>>>
>>>>>> Anyway you still need to restrict it per variant, as I said in previous
>>>>>> version.
>>>>> Hm.. I'm not entirely sure what you mean.. Should I add a list of
>>>>> compatibles
>>>> Yes and limit it to maxItems: 1 for "else".
>>>
>>> I tried adding:
>>>
>>>
>>>
>>>     - if:
>>>         properties:
>>>           compatible:
>>>             contains:
>>>               enum:
>>>                 - qcom,sm6375-smmu-500
>>>       then:
>>>         properties:
>>>           power-domains:
>>>             minItems: 3
>>>             maxItems: 3
>>>       else:
>>>         properties:
>>>           power-domains:
>>>             maxItems: 1
>>>
>>>
>>> Right under the nvidia reg if-else in the allOf, but dtbs_check throws
>>> errors like:
>>>
>>>
>>> /home/konrad/linux/arch/arm64/boot/dts/qcom/msm8998-sony-xperia-yoshino-poplar.dtb:
>>> iommu@...0000: 'power-domains' does not match any of the regexes:
>>> 'pinctrl-[0-9]+'
>>>
>>>
>>> Any clues as to why?
>>
>> I don't know what code do you have there, but generic pattern is:
>>
>> https://elixir.bootlin.com/linux/v5.19-rc6/source/Documentation/devicetree/bindings/clock/samsung,exynos7-clock.yaml#L38
>>
> I tried many things, but I still don't seem to get a hang of it.. Here's 
> my current diff rebased on top of Dmitry's recent cleanups (available at 
> [1])
> 
> 
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml 
> b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> index 28f5720824cd..55759aebc4a0 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> @@ -200,7 +200,7 @@ properties:
>       maxItems: 7
> 
>     power-domains:

As I mentioned before - minItems: 1.

Just like the link I gave you.

> -    maxItems: 1
> +    maxItems: 3
> 
>     nvidia,memory-controller:
>       description: |
> @@ -364,6 +364,26 @@ allOf:
>               - description: interface clock required to access smmu's 
> registers
>                   through the TCU's programming interface.
> 
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: qcom,sm6375-smmu-500
> +    then:
> +      properties:
> +        power-domains:
> +          items:
> +            - description: SNoC MMU TBU RT GDSC
> +            - description: SNoC MMU TBU NRT GDSC
> +            - description: SNoC TURING MMU TBU0 GDSC
> +
> +      required:
> +        - power-domains
> +    else:
> +      properties:
> +        power-domains:
> +          maxItems: 1
> +
>   examples:
>     - |+
>       /* SMMU with stream matching or stream indexing */
> 
> 
> In my eyes, this should work, but I still get errors like:
> 
> /home/konrad/linux/arch/arm64/boot/dts/qcom/sm8250-hdk.dtb: 
> iommu@...0000: power-domains: [[108, 0]] is too short
> 
> as if the else: path was never taken..

It was, but the top-level property said that minItems=3 (implicitly), so
it is too short.

Best regards,
Krzysztof