linux-kernel - Re: [PATCH] Allow selecting amd-pstate without CPU_SUP

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Message-ID: <YYqDhaXDIqJyjGjg@hr-amd>
Date:   Tue, 9 Nov 2021 22:19:49 +0800
From:   Huang Rui <ray.huang@....com>
To:     Stefano Picascia <stefano.picascia@...iberia.net>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Allow selecting amd-pstate without CPU_SUP_INTEL

O Mon, Nov 08, 2021 at 06:01:51PM +0800, Stefano Picascia wrote:
> On Mon, 2021-11-08 at 17:13 +0800, Huang Rui wrote:
> > On Sat, Nov 06, 2021 at 07:55:29PM +0800, Stefano Picascia wrote:
> > > Currently, even if selected, amd-pstate is not enabled unless
> > > CPU_SUP_INTEL is also selected, due to ACPI_CPPC_LIB depending on
> > > SCHED_MC_PRIO, which in turn depends on CPU_SUP_INTEL
> > 
> > Actually, amd-pstate driver doesn't depend on SCHED_MC_PRIO. 
> 
> amd-pstate doesn't depend on SCHED_MC_PRIO, but ACPI_CPPC_LIB is only
> selected when SCHED_MC_PRIO is selected. I guess the issue can be fixed
> in a better way, but currently if one compiles the kernel with
> CPU_SUP_AMD, but without CPU_SUP_INTEL, ends up with a non functional
> amd-pstate. 
> 
> Not a problem for distro kernels I guess, but I was puzzled as I wasn't
> getting amd-pstate even with a supported processor.
> 

If I modify the Kconfig of amd-pstate like below:

config X86_AMD_PSTATE
        bool "AMD Processor P-State driver"
        depends on X86
        select ACPI_PROCESSOR if ACPI
        select ACPI_CPPC_LIB if X86_64 && ACPI
        select CPU_FREQ_GOV_SCHEDUTIL if SMP

Then ACPI_CPPC_LIB can be selected by X86_AMD_PSTATE as well:

Symbol: ACPI_CPPC_LIB [=y]
Type  : bool

Defined at drivers/acpi/Kconfig:268
  Depends on: ACPI [=y] && ACPI_PROCESSOR [=y]
Selects: MAILBOX [=y] && PCC [=y]
Selected by [y]:
  - X86_AMD_PSTATE [=y] && CPU_FREQ [=y] && X86 [=y] && X86_64 [=y] && ACPI [=y]
Selected by [n]:
  - X86_INTEL_PSTATE [=n] && CPU_FREQ [=y] && X86 [=y] && X86_64 [=y] && ACPI [=y] && SCHED_MC_PRIO [=n]
  - ACPI_CPPC_CPUFREQ [=n] && CPU_FREQ [=y] && (ARM || ARM64) && ACPI_PROCESSOR [=y]

Did I miss anything?

Thanks,
Ray