[PATCH v3 1/6] dt-bindings: iommu: arm,smmu: Document interconnects property

[Dmitry Baryshkov]

On Mon, Jul 06, 2026 at 10:26:34PM +0530, Bibek Kumar Patro wrote:
> Some SoC implementations require a bandwidth vote on an interconnect
> path before the SMMU register space is accessible. Add the optional

Why is it limited only to those SoCs? Is it also applicable to other
Qualcomm SoCs?

> 'interconnects' property to the binding to allow platform DT nodes
> to describe this path.
> 
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>
> Signed-off-by: Bibek Kumar Patro <bibek.patro at oss.qualcomm.com>
> ---
>  .../devicetree/bindings/iommu/arm,smmu.yaml        | 27 ++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> index a701dec2fa0a..fab8944d7b63 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> @@ -246,6 +246,13 @@ properties:
>      minItems: 1
>      maxItems: 3
>  
> +  interconnects:
> +    maxItems: 1
> +    description:
> +      Interconnect path to the SMMU register space. Required on SoCs
> +      where the SMMU registers are only accessible after a bandwidth
> +      vote has been placed on the interconnect fabric.
> +
>    nvidia,memory-controller:
>      description: |
>        A phandle to the memory controller on NVIDIA Tegra186 and later SoCs.
> @@ -644,6 +651,26 @@ allOf:
>          clock-names: false
>          clocks: false
>  
> +  - if:
> +      properties:
> +        compatible:
> +          items:
> +            - enum:
> +                - qcom,qcs615-smmu-500
> +                - qcom,qcs8300-smmu-500
> +                - qcom,sa8775p-smmu-500
> +                - qcom,sc7280-smmu-500
> +            - const: qcom,adreno-smmu
> +            - const: qcom,smmu-500
> +            - const: arm,mmu-500

Can we be more idiomatic here?
Something like:

if:
  allOf:
    - properties:
        compatible:
          contains:
            enum:
              - qcom,qcs615-smmu-500
              - qcom,qcs8300-smmu-500
              - qcom,sa8775p-smmu-500
              - qcom,sc7280-smmu-500
    - properties:
        compatible:
          contains:
            const: qcom,adreno-smmu

In the end, we don't need to list the full list of compats. We need to
specify that it's Adreno SMMU on one of the listed platforms.


-- 
With best wishes
Dmitry