[Bug 218686] Fail to set energy_performance_preference of amd processor on asus ga403uv

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=218686

--- Comment #75 from Chema (chemasanchezgarabito@gmail.com) ---
(In reply to xiaojian.du from comment #74)
> I checked on my desktop PC, based on Asus B650M mainboard.
> 
> "Advanced option-> CPU option -> PSS disable/enable"is the switch option of
> CPPC.
> Disabling *PSS* option will make Win11 OS switch to generic ACPI processor
> pm management.
> 
> Back to this issue, somehow ASUS has enabled CPPC support in bios,as it
> showes "PSS ENABLED" in this video. 
>  https://bugzilla.kernel.org/attachment.cgi?id=306662
> 
> But the key CPUID bit of CPPC func enablement still is not written "1" in
> this new version BIOS, besides, the dmesg log shows the _cpc obj  in the
> ACPI table is null,
> "ACPI CPPC: _CPC in PCC is not supported".
> 
> So the conclusion is, CPPC func is enabled in this new version BIOS and Win
> OS is using it, but it doesn't support Linux OS.
> 
> Maybe ASUS didn't put too much notice to the user case on linux os?

Thanks for checking

It seems that way, asus has made it work in windows but not in the standard way
needed by linux. But either way the amd pstate driver is working, but the epp
change is not working.

What could be the easiest to try to solve it from our part, modifying the
kernel   in some way? If windows is working it should be a workaround to make
it work maybe disable some checks or something like this
https://github.com/archlinux/linux/blob/b1bc554e009e3aeed7e4cfd2e717c7a34a98c683/arch/x86/kernel/acpi/cppc.c#L14
or this
https://github.com/archlinux/linux/blob/defaf1a2113a22b00dfa1abc0fd2014820eaf065/drivers/acpi/cppc_acpi.c#L1491...?

Cause ASUS has not made any comment about it, I dont know from your part it
they have internally said something to you.

Thanks

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