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

[AMD Official Use Only]

-----Original Message-----
From: Fontenot, Nathan <redacted>
Sent: Wednesday, September 29, 2021 5:24 AM
To: Huang, Ray <Ray.Huang@amd.com>; Rafael J . Wysocki
[off-list ref]; Viresh Kumar [off-list ref];
Shuah Khan [off-list ref]; Borislav Petkov [off-list ref];
Peter Zijlstra [off-list ref]; Ingo Molnar [off-list ref];
linux-pm@vger.kernel.org
Cc: Sharma, Deepak <redacted>; Deucher, Alexander
[off-list ref]; Limonciello, Mario
[off-list ref]; Su, Jinzhou (Joe) [off-list ref];
Du, Xiaojian [off-list ref]; linux-kernel@vger.kernel.org;
x86@kernel.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:

quoted

The amd-pstate hardware support check will be needed by cpupower to

know

quoted

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