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

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Date:   Thu, 10 Dec 2020 16:04:40 +0100
From:   Mian Yousaf Kaukab <ykaukab@...e.de>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Mian Yousaf Kaukab <yousaf.kaukab@...e.com>,
        "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>,
        Petr Cervinka <pcervinka@...e.com>
Subject: Re: [PATCH 1/2] acpi: cppc: add cpufreq device

On Thu, Dec 10, 2020 at 03:32:09PM +0100, Rafael J. Wysocki wrote:
> On Thu, Dec 10, 2020 at 3:23 PM Mian Yousaf Kaukab
> <yousaf.kaukab@...e.com> wrote:
> >
> > 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.
> 
Even if we revert 28f06f770454 there is still one more small issue that these
patches fix. Currently, ACPI_PROCESSOR_DEVICE_HID is used to load cppc-cpufreq
module. In case when CPPC is disabled, some cycles will be wasted in loading
cppc-cpufreq module. The module will return error from the init call though
so no memory is wasted.

After converting to platform-driver, cppc-cpufreq module will only be loaded
when the platform-device is available.

BR,
Yousaf