linux-kernel - Re: [PATCH 2/2] cpufreq: don't call cpufreq_update

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Message-ID: <1725957.nHPERWcMfN@vostro.rjw.lan>
Date:	Mon, 17 Feb 2014 01:21:47 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linaro-kernel@...ts.linaro.org, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	pierre-list@...man.eu
Subject: Re: [PATCH 2/2] cpufreq: don't call cpufreq_update_policy() on CPU addition

On Friday, February 14, 2014 04:30:41 PM Viresh Kumar wrote:
> cpufreq_update_policy() is called from two places currently. From a workqueue
> handled queued from cpufreq_bp_resume() for boot CPU and from
> cpufreq_cpu_callback() whenever a CPU is added.
> 
> The first one makes sure that boot CPU is running on the frequency present in
> policy->cpu. But we don't really need a call from cpufreq_cpu_callback(),
> because we always call cpufreq_driver->init() (which will set policy->cur
> correctly) whenever first CPU of any policy is added back. And so every policy
> structure is guaranteed to have the right frequency in policy->cur.

That sounds good, but doing the extra cpufreq_update_policy() shouldn't actually
hurt, should it?

So, that would be a cleanup rather than a fix, right?

> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 383362b..b6eb4ed 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2194,7 +2194,6 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb,
>  		switch (action & ~CPU_TASKS_FROZEN) {
>  		case CPU_ONLINE:
>  			__cpufreq_add_dev(dev, NULL, frozen);
> -			cpufreq_update_policy(cpu);
>  			break;
>  
>  		case CPU_DOWN_PREPARE:
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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