linux-kernel - Re: [PATCH 1/2] acpi: processor: allow fixing up the frequency for a performance state

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Message-ID: <mafs0edsrdqw3.fsf_-_@amazon.de>
Date:   Thu, 22 Dec 2022 23:18:04 +0100
From:   Pratyush Yadav <ptyadav@...zon.de>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     <linux-pm@...r.kernel.org>, Len Brown <lenb@...nel.org>,
        "Srinivas Pandruvada" <srinivas.pandruvada@...ux.intel.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Robert Moore <robert.moore@...el.com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devel@...ica.org>
Subject: Re: [PATCH 1/2] acpi: processor: allow fixing up the frequency for
 a performance state

On Thu, Dec 22 2022, Rafael J. Wysocki wrote:
> On Wed, Dec 21, 2022 at 4:52 PM Pratyush Yadav <ptyadav@...zon.de> wrote:
>>
>> In some cases the ACPI table can have an incorrect frequency populated
>> for a performance state. For example, in Intel platforms, the Turbo
>> frequency is just listed as +1 MHz above the max non-turbo frequency.
>
> Which is a known convention based on compatibility with some older OSes.

Interesting. I did not know that.

>
>> The frequency can actually go much higher based on various factors like
>> temperature, voltage, etc.
>
> It can.
>
>> Allow drivers like intel_pstate to fix up performance state frequencies
>> with the actual maximum value.
>
> Why do you want to do that?

To be able to use my processors at the full frequency they are capable
of. See [0] for more details.

[0] https://lore.kernel.org/linux-pm/mafs0k02jd8oh.fsf_-_@dev-dsk-ptyadav-1c-37607b33.eu-west-1.amazon.com/

>
[...]

-- 
Regards,
Pratyush Yadav



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