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

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Date:   Tue, 15 Nov 2022 13:54:03 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...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 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:
-    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..

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=for-joerg/arm-smmu/bindings

Konrad
> Best regards,
> Krzysztof
>