linux-kernel - Re: [PATCH 1/2] acpi: cppc: add cpufreq device

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Message-ID: <CAJZ5v0hWxLrXCS+X15hnLZ2enBsSJ0aEfnxK2kL+n9k4gkg17Q@mail.gmail.com>
Date:   Thu, 10 Dec 2020 15:32:09 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mian Yousaf Kaukab <yousaf.kaukab@...e.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Mian Yousaf Kaukab <ykaukab@...e.de>,
        Petr Cervinka <pcervinka@...e.com>
Subject: Re: [PATCH 1/2] acpi: cppc: add cpufreq device

On Thu, Dec 10, 2020 at 3:23 PM Mian Yousaf Kaukab
<yousaf.kaukab@...e.com> wrote:
>
> From: Mian Yousaf Kaukab <ykaukab@...e.de>
>
> Since commit 28f06f770454 ("cppc_cpufreq: replace per-cpu structures with
> lists"), cppc-cpufreq driver doesn't check availability of PSD data before
> registering with cpufreq core. As a result on a ThunderX2 platform when
> CPPC is disabled from BIOS, kernel log is spammed with following messages:
>
> [  180.974166] CPPC Cpufreq: Error in acquiring _CPC/_PSD data for CPUxx
>
> acpi_cppc_processor_probe() never succeed in this case because
> acpi_evaluate_object_typed("_CPC") always returns AE_NOT_FOUND. When
> cpufreq core calls cppc_cpufreq_cpu_init(), driver fails to obtain PSD data
> and print error messages.
>
> Convert cppc-cpufreq driver to a platform driver (done in a separate patch)
> and add cppc-cpufreq device when acpi_cppc_processor_probe() succeeds.

Honestly, I prefer to drop 28f06f770454 (along with its follower)
instead of making this change.

> Fixes: 28f06f770454 ("cppc_cpufreq: replace per-cpu structures with lists")

Thanks!