linux-kernel - Re: [PATCH v2 1/3] cpufreq: add resolve

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Message-ID: <20160531181253.GI9864@graphite.smuckle.net>
Date:	Tue, 31 May 2016 11:12:53 -0700
From:	Steve Muckle <steve.muckle@...aro.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Steve Muckle <steve.muckle@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Juri Lelli <Juri.Lelli@....com>,
	Patrick Bellasi <patrick.bellasi@....com>,
	Michael Turquette <mturquette@...libre.com>
Subject: Re: [PATCH v2 1/3] cpufreq: add resolve_freq driver callback

On Tue, May 31, 2016 at 04:44:51PM +0530, Viresh Kumar wrote:
> On 25-05-16, 19:52, Steve Muckle wrote:
> > +unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
> > +					 unsigned int target_freq)
> > +{
> > +	struct cpufreq_frequency_table *freq_table;
> > +	int index, retval;
> > +
> > +	clamp_val(target_freq, policy->min, policy->max);
> 
> Rafael will kill me for this, as I have fallen into the same trap and
> copied your *incorrect* code :(
> 
> This is a useless statement unless you do:
> 
> target_freq = clamp_val(target_freq, policy->min, policy->max);

Well I wouldn't worry too much, I copied it from Rafael's code in
cpufreq_driver_fast_switch() which also has this problem and needs to be
fixed.

Perhaps clamp_val could be changed to force the compiler to check that
its return value is being used.

thanks,
Steve