Re: [PATCH 01/12] dt-bindings: iommu: qcom,iommu: document the MSM8974 IOMMUs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] Missing top-level 'interrupts' property and incorrect unconditional requirements for new direct-mapped instances.
- [Low] The schema fails to conditionally require the `reg` property for the newly added MSM8974 per-instance compatibles.
--

--- Patch [1]: [PATCH 01/12] dt-bindings: iommu: qcom,iommu: document the MSM8974 IOMMUs ---
commit b29444ad6a6fa61aa71980a7c581393333c88d6a
Author: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

dt-bindings: iommu: qcom,iommu: document the MSM8974 IOMMUs

This patch adds per-instance compatibles for the display, Venus and GPU
MSM8974 IOMMU instances based on the ARM SMMU v1 spec. It allows the driver
to carry per-instance prefetch tuning tables and stream ID maps, and updates
property documentation for direct-mapped instances.

> diff --git a/Documentation/devicetree/bindings/iommu/qcom,iommu.yaml b/Documentation/devicetree/bindings/iommu/qcom,iommu.yaml
> index 93a4890253170..43dffe41e3b8f 100644
> --- a/Documentation/devicetree/bindings/iommu/qcom,iommu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/qcom,iommu.yaml
> @@ -30,6 +30,10 @@ properties:
>                - qcom,msm8953-iommu
>                - qcom,msm8976-iommu
>            - const: qcom,msm-iommu-v2
> +      - enum:
> +          - qcom,msm8974-gpu-iommu
> +          - qcom,msm8974-mdp-iommu
> +          - qcom,msm8974-venus-iommu

[Severity: Medium]
Will valid configurations for these direct-mapped instances fail schema
validation when qcom,iommu-secure-id is missing?

If the OS programs the global register space directly, statically assigned
iommu-ctx@ child nodes aren't used, requiring interrupts to be defined at the
top level. Because interrupts is not defined at the top level and child node
properties are unconditionally required, adding a node for these compatibles
without qcom,iommu-secure-id appears to fail dt_binding_check.

Could the global schema constraints be adjusted to allow top-level interrupts
and conditionally relax child-node requirements for these new non-secured
instances?

[ ... ]

> @@ -50,13 +54,23 @@ properties:
>  
>    reg:
>      maxItems: 1
> +    description:
> +      For instances using the qcom,msm-iommu-v1/-v2 fallbacks, the
> +      optional "SMMU local" register region used for interrupt routing
> +      configuration. For instances with per-instance compatibles, the
> +      SMMU global register space, used for stream mapping configuration
> +      on non-secured instances and for the implementation-defined
> +      prefetch registers on all instances.

[Severity: Low]
Is a conditional allOf block missing to enforce the presence of the reg
property for the new MSM8974 per-instance compatibles?

The description states that reg is used for the implementation-defined
prefetch registers on all instances with per-instance compatibles. Without
requiring it conditionally, incomplete device tree nodes missing the reg
property will silently pass validation.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260809-msm8974-iommu-upstream-v1-0-87f5cd492560@oss.qualcomm.com?part=1