linux-kernel - Re: [PATCH v4 2/9] cpufreq: Auto-register the driver as a thermal cooling device if asked

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Date:   Mon, 28 Jan 2019 10:03:19 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Amit Kucheria <amit.kucheria@...aro.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Tao Wang <kevin.wangtao@...ilicon.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v4 2/9] cpufreq: Auto-register the driver as a thermal
 cooling device if asked

On Mon, Jan 28, 2019 at 7:44 AM Amit Kucheria <amit.kucheria@...aro.org> wrote:
>
> All cpufreq drivers do similar things to register as a cooling device.
> Provide a cpufreq driver flag so drivers can just ask the cpufreq core
> to register the cooling device on their behalf. This allows us to get
> rid of duplicated code in the drivers.
>
> In order to allow this, we add a struct thermal_cooling_device pointer
> to struct cpufreq_policy so that drivers don't need to store it in a
> private data structure.
>
> Suggested-by: Stephen Boyd <swboyd@...omium.org>
> Suggested-by: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> Tested-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  drivers/cpufreq/cpufreq.c | 9 +++++++++
>  include/linux/cpufreq.h   | 9 +++++++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e35a886e00bc..29ed78b0b77b 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -19,6 +19,7 @@
>
>  #include <linux/cpu.h>
>  #include <linux/cpufreq.h>
> +#include <linux/cpu_cooling.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/init.h>
> @@ -1318,6 +1319,9 @@ static int cpufreq_online(unsigned int cpu)
>         if (cpufreq_driver->ready)
>                 cpufreq_driver->ready(policy);
>
> +       if (cpufreq_driver->flags & CPUFREQ_AUTO_REGISTER_COOLING_DEV)

It would be good to use IS_ENABLED(CONFIG_CPU_THERMAL) here and below
as a hint for the compiler.

> +               policy->cdev = of_cpufreq_cooling_register(policy);
> +
>         pr_debug("initialization complete\n");
>
>         return 0;
> @@ -1405,6 +1409,11 @@ static int cpufreq_offline(unsigned int cpu)
>                 goto unlock;
>         }
>
> +       if (cpufreq_driver->flags & CPUFREQ_AUTO_REGISTER_COOLING_DEV) {
> +               cpufreq_cooling_unregister(policy->cdev);
> +               policy->cdev = NULL;
> +       }
> +
>         if (cpufreq_driver->stop_cpu)
>                 cpufreq_driver->stop_cpu(policy);
>