linux-kernel - Re: [PATCH v4 02/10] cpufreq: provide default frequency-invariance setter function

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Message-ID: <2495043.bolhgyT0yC@aspire.rjw.lan>
Date:   Fri, 08 Sep 2017 01:22:54 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux@....linux.org.uk,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Juri Lelli <juri.lelli@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v4 02/10] cpufreq: provide default frequency-invariance setter function

On Friday, August 25, 2017 4:31:58 PM CEST Dietmar Eggemann wrote:
> Frequency-invariant accounting support based on the ratio of current
> frequency and maximum supported frequency is an optional feature an arch
> can implement.
> 
> Since there are cpufreq drivers (e.g. cpufreq-dt) which can be build for
> different arch's a default implementation of the frequency-invariance
> setter function arch_set_freq_scale() is needed.
> 
> This default implementation is an empty weak function which will be
> overwritten by a strong function in case the arch provides one.
> 
> The setter function passes the cpumask of related (to the frequency
> change) cpus (online and offline cpus), the (new) current frequency and
> the maximum supported frequency.
> 
> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/cpufreq/cpufreq.c | 6 ++++++
>  include/linux/cpufreq.h   | 3 +++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 9bf97a366029..ced8d539d0d5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -161,6 +161,12 @@ u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
>  }
>  EXPORT_SYMBOL_GPL(get_cpu_idle_time);
>  
> +__weak void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
> +		unsigned long max_freq)
> +{
> +}
> +EXPORT_SYMBOL_GPL(arch_set_freq_scale);
> +
>  /*
>   * This is a generic cpufreq init() routine which can be used by cpufreq
>   * drivers of SMP systems. It will do following:
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index f10a9b3761cd..e38acc1a4d47 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -899,6 +899,9 @@ static inline bool policy_has_boost_freq(struct cpufreq_policy *policy)
>  
>  extern unsigned int arch_freq_get_on_cpu(int cpu);
>  
> +extern void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
> +				unsigned long max_freq);
> +
>  /* the following are really really optional */
>  extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
>  extern struct freq_attr cpufreq_freq_attr_scaling_boost_freqs;
>