linux-kernel - Re: [PATCH v1 5/7] cpufreq: qcom-hw: Register as a cpufreq cooling device

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Date:   Thu, 10 Jan 2019 11:42:10 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Amit Kucheria <amit.kucheria@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        bjorn.andersson@...aro.org, edubezval@...il.com,
        andy.gross@...aro.org, tdas@...eaurora.org, swboyd@...omium.org,
        dianders@...omium.org, mka@...omium.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "open list:CPU FREQUENCY DRIVERS" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v1 5/7] cpufreq: qcom-hw: Register as a cpufreq cooling
 device

On 10-01-19, 05:30, Amit Kucheria wrote:
> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> ---
>  drivers/cpufreq/qcom-cpufreq-hw.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 649dddd72749..1c01311e5927 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -5,6 +5,7 @@
>  
>  #include <linux/bitfield.h>
>  #include <linux/cpufreq.h>
> +#include <linux/cpu_cooling.h>
>  #include <linux/init.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> @@ -216,7 +217,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>  static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
>  {
>  	void __iomem *base = policy->driver_data - REG_PERF_STATE;
> +	struct thermal_cooling_device *cdev = policy->cooldev;
>  
> +	if (cdev)
> +		cpufreq_cooling_unregister(cdev);
>  	kfree(policy->freq_table);
>  	devm_iounmap(&global_pdev->dev, base);
>  
> @@ -238,6 +242,7 @@ static struct cpufreq_driver cpufreq_qcom_hw_driver = {
>  	.init		= qcom_cpufreq_hw_cpu_init,
>  	.exit		= qcom_cpufreq_hw_cpu_exit,
>  	.fast_switch    = qcom_cpufreq_hw_fast_switch,
> +	.ready		= generic_cpufreq_ready,
>  	.name		= "qcom-cpufreq-hw",
>  	.attr		= qcom_cpufreq_hw_attr,
>  };

I liked the idea of reducing code duplication, but not much the
implementation. All we were able to get rid of was a call to
of_cpufreq_cooling_register() and nothing else. Is it worth it ?

Maybe we can add another flag in cpufreq.h:

#define CPUFREQ_AUTO_REGISTER_COOLING_DEV (1 << 7)

and let the core do it all automatically by itself, that will get rid
of code duplication actually.

@Rafael: What do you say ?

-- 
viresh