linux-kernel - Re: [Suggested-by:Shuah Khan Patch 1/1] cpufreq: amd-pstate: Add explanation for X86_AMD_PSTATE

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Date:   Thu, 1 Sep 2022 09:47:06 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Meng Li <li.meng@....com>, Huang Rui <ray.huang@....com>,
        linux-pm@...r.kernel.org
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Nathan Fontenot <nathan.fontenot@....com>,
        Deepak Sharma <deepak.sharma@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Jinzhou Su <Jinzhou.Su@....com>,
        Perry Yuan <Perry.Yuan@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [Suggested-by:Shuah Khan Patch 1/1] cpufreq: amd-pstate: Add
 explanation for X86_AMD_PSTATE_UT

On 9/1/22 08:33, Meng Li wrote:
> This kernel module is used for testing. It's safe to say M here.
> It can be modprobed even without amd-pstate module.
> When the comparison test is performed, it can load other module
> like acpi-cpufreq to test cases, then compare the test  results.
> When only the test for amd-pstate is performed, it can tell the
> users they loaded a wrong module like acpi-cpufreq.
> 
> Signed-off-by: Meng Li <li.meng@....com>
> ---
>   drivers/cpufreq/Kconfig.x86 | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
> index fdd819069d72..fd1582716c58 100644
> --- a/drivers/cpufreq/Kconfig.x86
> +++ b/drivers/cpufreq/Kconfig.x86
> @@ -58,6 +58,12 @@ config X86_AMD_PSTATE_UT
>   	help
>   	  This kernel module is used for testing. It's safe to say M here.
>   
> +	  It can be modprobed even without amd-pstate module.

It can also be built-in without X86_AMD_PSTATE enabled.
I would rephrase this as:

This config option can be enabled without X86_AMD_PSTATE enabled.

Also change the information below to sat enabled as opposed to module
as both these options can be built-in

> +	  When the comparison test is performed, it can load other module
> +	  like acpi-cpufreq to test cases, then compare the test results.
> +	  When only the test for amd-pstate is performed, it can tell the
> +	  users they loaded a wrong module like acpi-cpufreq.
> +
>   config X86_ACPI_CPUFREQ
>   	tristate "ACPI Processor P-States driver"
>   	depends on ACPI_PROCESSOR

Thank you - In addition to this patch please make change to the test
script as well when it fails detecting that X86_AMD_PSTATE is disabled
to say what user has to do to run the test.

This run-time message will be helpful to users.

thanks,
-- Shuah