Re: [PATCH v1 1/2] iommu/tegra-smmu: Defer attachment of display clients

Dmitry Osipenko
2021-04-09T12:55:48Z

08.04.2021 17:07, Dmitry Osipenko пишет:
>> Whatever happened to the idea of creating identity mappings based on the
>> obscure tegra_fb_mem (or whatever it was called) command-line option? Is
>> that command-line not universally passed to the kernel from bootloaders
>> that initialize display?
> This is still a good idea! The command-line isn't universally passed
> just because it's up to a user to override the cmdline and then we get a
> hang (a very slow boot in reality) on T30 since display client takes out
> the whole memory bus with the constant SMMU faults. For example I don't
> have that cmdline option in my current setups.
>

Thinking a bit more about the identity.. have you consulted with the
memory h/w people about whether it's always safe to enable ASID in a
middle of DMA request?