On 01/07/2020 20:00, Krishna Reddy wrote:
>>>>> +        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.
>> The problem is, if for some reason someone had a Tegra194, but only set the 
>> compatible string to 'arm,mmu-500' it would assume that it was a normal 
>> arm,mmu-500 and only one instance would be programmed. We always want at 
>> least 2 of the 3 instances >programmed and so we should only match 
>> 'nvidia,tegra194-smmu'. In fact, I think that we also need to update the 
>> arm_smmu_of_match table to add 'nvidia,tegra194-smmu' with the data set to 
>> &arm_mmu500.
> In that case, new binding "nvidia,smmu-v2" can be added with data set to 
> &arm_mmu500 and enumeration would have nvidia,tegra194-smmu and another 
> variant for next generation SoC in future. 

I think you would be better off with nvidia,smmu-500 as smmu-v2 appears
to be something different. I see others have a smmu-v2 but I am not sure
if that is legacy. We have an smmu-500 and so that would seem more


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