linux-kernel - Re: [PATCH V2 1/2] cpufreq: ondemand: allow custom powersave_bias

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Date:	Tue, 2 Apr 2013 14:43:32 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Jacob Shin <jacob.shin@....com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH V2 1/2] cpufreq: ondemand: allow custom
 powersave_bias_target function to be registered

On Thu, Mar 28, 2013 at 01:24:16PM -0500, Jacob Shin wrote:
> This allows for another [arch specific] driver to hook into existing
> powersave bias function of the ondemand governor. i.e. This allows AMD
> specific powersave bias function (in a separate AMD specific driver)
> to aid ondemand governor's frequency transition deicisions.
> 
> Signed-off-by: Jacob Shin <jacob.shin@....com>
> ---
>  drivers/cpufreq/cpufreq_governor.h |    3 +++
>  drivers/cpufreq/cpufreq_ondemand.c |   22 +++++++++++++++++++---
>  2 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
> index c83cabf..4b6808f 100644
> --- a/drivers/cpufreq/cpufreq_governor.h
> +++ b/drivers/cpufreq/cpufreq_governor.h
> @@ -262,4 +262,7 @@ bool need_load_eval(struct cpu_dbs_common_info *cdbs,
>  		unsigned int sampling_rate);
>  int cpufreq_governor_dbs(struct cpufreq_policy *policy,
>  		struct common_dbs_data *cdata, unsigned int event);
> +void od_register_powersave_bias_function(unsigned int (*f)
> +		(struct cpufreq_policy *, unsigned int, unsigned int));
> +void od_unregister_powersave_bias_function(void);

We generally call those a "callback" or a "handler". I.e.,
od_register_powersave_bias_handler or something.

>  #endif /* _CPUFREQ_GOVERNER_H */
> diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
> index 15e80ee..36f0798 100644
> --- a/drivers/cpufreq/cpufreq_ondemand.c
> +++ b/drivers/cpufreq/cpufreq_ondemand.c
> @@ -40,6 +40,8 @@
>  
>  static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
>  
> +static struct od_ops od_ops;
> +
>  #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
>  static struct cpufreq_governor cpufreq_gov_ondemand;
>  #endif
> @@ -145,7 +147,8 @@ static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
>  	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
>  
>  	if (od_tuners->powersave_bias)
> -		freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
> +		freq = od_ops.powersave_bias_target(p, freq,
> +				CPUFREQ_RELATION_H);
>  	else if (p->cur == p->max)
>  		return;
>  
> @@ -206,8 +209,8 @@ static void od_check_cpu(int cpu, unsigned int load_freq)
>  			__cpufreq_driver_target(policy, freq_next,
>  					CPUFREQ_RELATION_L);
>  		} else {
> -			int freq = powersave_bias_target(policy, freq_next,
> -					CPUFREQ_RELATION_L);
> +			int freq = od_ops.powersave_bias_target(policy,
> +					freq_next, CPUFREQ_RELATION_L);
>  			__cpufreq_driver_target(policy, freq,
>  					CPUFREQ_RELATION_L);
>  		}
> @@ -565,6 +568,19 @@ static struct common_dbs_data od_dbs_cdata = {
>  	.exit = od_exit,
>  };
>  
> +void od_register_powersave_bias_function(unsigned int (*f)
> +		(struct cpufreq_policy *, unsigned int, unsigned int))
> +{
> +	od_ops.powersave_bias_target = f;
> +}
> +EXPORT_SYMBOL_GPL(od_register_powersave_bias_function);
> +
> +void od_unregister_powersave_bias_function(void)
> +{
> +	od_ops.powersave_bias_target = powersave_bias_target;

This is very confusing: we have ->powersave_bias_target and the default
powersave_bias_target in the ondemand governor. Can we call the default
one generic_powersave_bias_target or default_* or whatever.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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