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

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Message-ID: <700a92d942e3b9455d82a9833efd1f6db78dc500.camel@insiberia.net>
Date:   Wed, 10 Nov 2021 09:12:11 +0000
From:   Stefano Picascia <stefano.picascia@...iberia.net>
To:     Huang Rui <ray.huang@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Allow selecting amd-pstate without CPU_SUP_INTEL

On Tue, 2021-11-09 at 22:19 +0800, Huang Rui wrote:
> 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?


Works perfectly.
Thank you very much