RE: [PATCH v8 2/3] dt-bindings: arm-smmu: Add binding for Tegra194 SMMU

From: Krishna Reddy
Date: Wed Jul 01 2020 - 14:29:11 EST


>> + - description: NVIDIA SoCs that use more than one "arm,mmu-500"
> Hmm, there must be a better way to word that to express that it only applies to the sets of SMMUs that must be programmed identically, and not any other independent MMU-500s that might also happen to be in the same SoC.

Let me reword it to "NVIDIA SoCs that must program multiple MMU-500s identically".

>> + items:
>> + - enum:
>> + - nvdia,tegra194-smmu
>> + - const: arm,mmu-500

>Is the fallback compatible appropriate here? If software treats this as a standard MMU-500 it will only program the first instance (because the second isn't presented as a separate MMU-500) - is there any way that isn't going to blow up?

When compatible is set to both nvidia,tegra194-smmu and arm,mmu-500, implementation override ensure that both instances are programmed. Isn't it? I am not sure I follow your comment fully.

-KR