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

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On 2022-11-15 13:06, Konrad Dybcio wrote:


On 15/11/2022 14:00, Krzysztof Kozlowski wrote:
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@xxxxxxxxxx>
---
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@5040000: '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.
But not all SMMUs require a power domain :/

Right, so it's not a required property. However if it *is* present, then it needs to reference at least one power domain, because having an empty property, i.e.:

	power-domains = <>;

or
	power-domains;

makes no sense whatsoever.

Thanks,
Robin.



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@3da0000: 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.
So the top-level properties take precedence over the ones that come from the if-then-else?? Ugh.

Konrad

Best regards,
Krzysztof




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