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Date:   Fri, 25 Jan 2019 16:01:52 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Amit Kucheria <amit.kucheria@linaro.org>
Cc:     linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        edubezval@gmail.com, swboyd@chromium.org, dianders@chromium.org,
        mka@chromium.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "open list:CPU FREQUENCY SCALING FRAMEWORK" 
        <linux-pm@vger.kernel.org>
Subject: Re: [PATCHv3 2/9] cpufreq: Auto-register the driver as a thermal
 cooling device if asked
Message-ID: <20190125103152.7svjfmowgigznipm@vireshk-i7>
References: <cover.1548398851.git.amit.kucheria@linaro.org>
 <73e091e2d56d9fa6eb94feaed9fc2be30bf6da20.1548398851.git.amit.kucheria@linaro.org>
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On 25-01-19, 12:32, Amit Kucheria 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@chromium.org>
> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org>
> Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> Tested-by: Matthias Kaehlcke <mka@chromium.org>
> ---
>  drivers/cpufreq/cpufreq.c |  6 ++++++
>  include/linux/cpufreq.h   | 21 +++++++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e35a886e00bc..cf1be057caf4 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1318,6 +1318,9 @@ static int cpufreq_online(unsigned int cpu)
>  	if (cpufreq_driver->ready)
>  		cpufreq_driver->ready(policy);
>  
> +	if (cpufreq_driver->flags & CPUFREQ_AUTO_REGISTER_COOLING_DEV)
> +		register_cooling_device(policy);
> +
>  	pr_debug("initialization complete\n");
>  
>  	return 0;
> @@ -1405,6 +1408,9 @@ static int cpufreq_offline(unsigned int cpu)
>  		goto unlock;
>  	}
>  
> +	if (cpufreq_driver->flags & CPUFREQ_AUTO_REGISTER_COOLING_DEV)
> +		unregister_cooling_device(policy);
> +
>  	if (cpufreq_driver->stop_cpu)
>  		cpufreq_driver->stop_cpu(policy);
>  
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index bd7fbd6a4478..c7eb59b8ce94 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -13,6 +13,7 @@
>  
>  #include <linux/clk.h>
>  #include <linux/cpumask.h>
> +#include <linux/cpu_cooling.h>
>  #include <linux/completion.h>
>  #include <linux/kobject.h>
>  #include <linux/notifier.h>
> @@ -151,6 +152,9 @@ struct cpufreq_policy {
>  
>  	/* For cpufreq driver's internal use */
>  	void			*driver_data;
> +
> +	/* Pointer to the cooling device if used for thermal mitigation */
> +	struct thermal_cooling_device *cdev;
>  };
>  
>  /* Only for ACPI */
> @@ -386,6 +390,12 @@ struct cpufreq_driver {
>   */
>  #define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING	BIT(6)
>  
> +/*
> + * Set by drivers that want the core to automatically register the cpufreq
> + * driver as a thermal cooling device.
> + */
> +#define CPUFREQ_AUTO_REGISTER_COOLING_DEV	BIT(7)
> +
>  int cpufreq_register_driver(struct cpufreq_driver *driver_data);
>  int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
>  
> @@ -415,6 +425,17 @@ cpufreq_verify_within_cpu_limits(struct cpufreq_policy *policy)
>  			policy->cpuinfo.max_freq);
>  }
>  
> +static inline void register_cooling_device(struct cpufreq_policy *policy)
> +{
> +	policy->cdev = of_cpufreq_cooling_register(policy);
> +}
> +
> +static inline void unregister_cooling_device(struct cpufreq_policy *policy)
> +{
> +	cpufreq_cooling_unregister(policy->cdev);
> +	policy->cdev = NULL;
> +}

I thought that we discussed over chat that you wouldn't add any
wrapper routines. How do you see these getting used ? I will suggest
that this should be open coded in the core itself.

-- 
viresh