linux-kernel - RE: [PATCH v2 10/21] cpufreq: amd: add amd-pstate checking support check attribute

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Message-ID: <CY4PR1201MB0246BE2C3BDBFD575E3BE390ECB89@CY4PR1201MB0246.namprd12.prod.outlook.com>
Date:   Thu, 14 Oct 2021 10:26:07 +0000
From:   "Huang, Ray" <Ray.Huang@....com>
To:     "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
CC:     "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "Su, Jinzhou (Joe)" <Jinzhou.Su@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: RE: [PATCH v2 10/21] cpufreq: amd: add amd-pstate checking support
 check attribute

[AMD Official Use Only]

> -----Original Message-----
> From: Fontenot, Nathan <Nathan.Fontenot@....com>
> Sent: Wednesday, September 29, 2021 5:24 AM
> To: Huang, Ray <Ray.Huang@....com>; Rafael J . Wysocki
> <rafael.j.wysocki@...el.com>; Viresh Kumar <viresh.kumar@...aro.org>;
> Shuah Khan <skhan@...uxfoundation.org>; Borislav Petkov <bp@...e.de>;
> Peter Zijlstra <peterz@...radead.org>; Ingo Molnar <mingo@...nel.org>;
> linux-pm@...r.kernel.org
> Cc: Sharma, Deepak <Deepak.Sharma@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Limonciello, Mario
> <Mario.Limonciello@....com>; Su, Jinzhou (Joe) <Jinzhou.Su@....com>;
> Du, Xiaojian <Xiaojian.Du@....com>; linux-kernel@...r.kernel.org;
> x86@...nel.org
> Subject: Re: [PATCH v2 10/21] cpufreq: amd: add amd-pstate checking
> support check attribute
> 
> On 9/26/2021 4:05 AM, Huang Rui wrote:
> > The amd-pstate hardware support check will be needed by cpupower to
> know
> > whether amd-pstate is enabled and supported.
> >
> 
> Is this needed?
> 
> If acpi_cpc_valid() is false, then the amd_pstate driver would not have been
> loaded (see patch 5/21, module init routine will return -ENODEV). If this
> driver isn't loaded then this sysfs file won't get created.
> 
> Shouldn't the cpupower command just check the scaling_driver in sysfs to
> see
> if it's amd_pstate?
> 

Make sense, thanks! Will update it in V3.

Thanks,
Ray