Re: [PATCH v5 0/3] arm64: qcom: sa8775p: add cache coherency support for SA8775P

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On 2/24/2024 3:49 PM, Krzysztof Kozlowski wrote:
On 23/02/2024 15:03, Mrinmay Sarkar wrote:
Due to some hardware changes, SA8775P has set the NO_SNOOP attribute
in its TLP for all the PCIe controllers. NO_SNOOP attribute when set,
the requester is indicating that there no cache coherency issues exit
for the addressed memory on the host i.e., memory is not cached. But
in reality, requester cannot assume this unless there is a complete
control/visibility over the addressed memory on the host.

And worst case, if the memory is cached on the host, it may lead to
memory corruption issues. It should be noted that the caching of memory
on the host is not solely dependent on the NO_SNOOP attribute in TLP.

So to avoid the corruption, this patch overrides the NO_SNOOP attribute
by setting the PCIE_PARF_NO_SNOOP_OVERIDE register. This patch is not
needed for other upstream supported platforms since they do not set
NO_SNOOP attribute by default.

This series is to enable cache snooping logic in both RC and EP driver
and add the "dma-coherent" property in dtsi to support cache coherency
in SA8775P platform.
Please confirm that your patchset passes 100% dtbs_check.

Best regards,

I have run dtbs_check and it is passing.


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