Re: [PATCH 10/20] dt-bindings: arm-smmu: Add compatible string for Adreno GPU SMMU
From: Doug Anderson <dianders@chromium.org>
Date: 2020-08-19 17:03:42
Also in:
dri-devel, linux-arm-msm, linux-devicetree, linux-iommu, lkml
Hi, On Mon, Aug 17, 2020 at 3:03 PM Rob Clark [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Jordan Crouse <redacted> Every Qcom Adreno GPU has an embedded SMMU for its own use. These devices depend on unique features such as split pagetables, different stall/halt requirements and other settings. Identify them with a compatible string so that they can be identified in the arm-smmu implementation specific code. Signed-off-by: Jordan Crouse <redacted> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Rob Clark <redacted> --- Documentation/devicetree/bindings/iommu/arm,smmu.yaml | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml index 503160a7b9a0..5ec5d0d691f6 100644 --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml@@ -40,6 +40,10 @@ properties: - qcom,sm8150-smmu-500 - qcom,sm8250-smmu-500 - const: arm,mmu-500 + - description: Qcom Adreno GPUs implementing "arm,smmu-v2" + items: + - const: qcom,adreno-smmu + - const: qcom,smmu-v2
I know I'm kinda late to the game, but this seems weird to me, especially given the later patches in the series like: https://lore.kernel.org/r/20200817220238.603465-19-robdclark@gmail.com (local) Specifically in that patch you can see that this IOMMU already had a compatible string and we're changing it and throwing away the model-specific string? I'm guessing that you're just trying to make it easier for code to identify the adreno iommu, but it seems like a better way would have been to just add the adreno compatible in the middle, like: - description: Qcom Adreno GPUs implementing "arm,smmu-v2" items: - enum: - qcom,msm8996-smmu-v2 - qcom,msm8998-smmu-v2 - qcom,sc7180-smmu-v2 - qcom,sdm845-smmu-v2 - const: qcom,adreno-smmu - const: qcom,smmu-v2 Then we still have the SoC-specific compatible string in case we need it but we also have the generic one? It also means that we're not deleting the old compatible string... -Doug
- description: Marvell SoCs implementing "arm,mmu-500"
items:
- const: marvell,ap806-smmu-500
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