linux-kernel - Re: [PATCH 1/5] cpufreq: handle SW coordinated CPUs

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Date:	Wed, 30 Jan 2013 12:04:29 +0100
From:	Fabio Baltieri <fabio.baltieri@...aro.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, Linus Walleij <linus.walleij@...aro.org>,
	linux-kernel@...r.kernel.org,
	Rickard Andersson <rickard.andersson@...ricsson.com>,
	linaro-dev@...ts.linaro.org
Subject: Re: [PATCH 1/5] cpufreq: handle SW coordinated CPUs

On Wed, Jan 30, 2013 at 10:14:53AM +0100, Fabio Baltieri wrote:
> Hello Viresh,
> 
> On Wed, Jan 30, 2013 at 12:33:40PM +0530, Viresh Kumar wrote:
> > I am starting to follow cpufreq patches religiously now and so have to come
> > back to this old thread due to some crash we got :)
> > 
> > Its still not pushed upstream, so better to get it resolved before 3.9.
> 
> Definitely, that's what we have -next for!
> 
> > On Thu, Dec 27, 2012 at 8:25 PM, Fabio Baltieri
> > <fabio.baltieri@...aro.org> wrote:
> > 
> > > diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
> > 
> > >  static inline void dbs_timer_init(struct dbs_data *dbs_data,
> > > -               struct cpu_dbs_common_info *cdbs, unsigned int sampling_rate)
> > > +                                 struct cpu_dbs_common_info *cdbs,
> > > +                                 unsigned int sampling_rate,
> > > +                                 int cpu)
> > >  {
> > >         int delay = delay_for_sampling_rate(sampling_rate);
> > > +       struct cpu_dbs_common_info *cdbs_local = dbs_data->get_cpu_cdbs(cpu);
> > 
> > I couldn't understand the real need for this, as it should really give
> > back the same
> > pointer pointed out by: cdbs and hence no need of cpu in params too..

Small sidenote, actually what I'm going to drop here i *cdbs, as I need
cpu for schedule_delayed_work_on and can't use cdbs->cpu for that as
it's the master's one.

Fabio

> > 
> > I may be wrong here :)
> 
> You are actually right.  This comes from the first version of the patch
> (I basically rewrote it after the common code rafactoring), and cdbs was
> meant to be always the one for the master CPU while cpu should indicate
> the one being initialized.  Then the thing turned out as:
> 
> A - I dropped the code specific for master cdbs here as it was already
> there on another code path following the rafactoring.
> B - I passed j_cdbs = dbs_data->get_cpu_cdbs(j) in the init cycle while
> it was really meant to be get_cpu_cdbs(cpu).
> 
> > >
> > > -       INIT_DEFERRABLE_WORK(&cdbs->work, dbs_data->gov_dbs_timer);
> > > -       schedule_delayed_work_on(cdbs->cpu, &cdbs->work, delay);
> > > +       schedule_delayed_work_on(cpu, &cdbs_local->work, delay);
> > >  }

-- 
Fabio Baltieri
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