linux-kernel - Re: [PATCH 206/228] cpufreq: sa11x0: remove calls to cpufreq_notify

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Date:	Fri, 13 Sep 2013 17:15:28 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Patch Tracking <patches@...aro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 206/228] cpufreq: sa11x0: remove calls to
	cpufreq_notify_transition()

On Fri, Sep 13, 2013 at 09:42:23PM +0530, Viresh Kumar wrote:
> On 13 September 2013 21:24, Russell King - ARM Linux
> <linux@....linux.org.uk> wrote:
> > On Fri, Sep 13, 2013 at 06:32:32PM +0530, Viresh Kumar wrote:
> >> Most of the drivers do following in their ->target_index() routines:
> >>
> >>       struct cpufreq_freqs freqs;
> >>       freqs.old = old freq...
> >>       freqs.new = new freq...
> >>
> >>       cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
> >>
> >>       /* Change rate here */
> >>
> >>       cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
> >>
> >> This is replicated over all cpufreq drivers today and there doesn't exists a
> >> good enough reason why this shouldn't be moved to cpufreq core instead.
> >>
> >> Earlier patches have added support in cpufreq core to do cpufreq notification on
> >> frequency change, this one removes it from this driver.
> >>
> >> Some related minor cleanups are also done along with it.
> >>
> >> Cc: Russell King <linux@....linux.org.uk>
> >> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> >
> > Shouldn't this patch set CPUFREQ_ASYNC_NOTIFICATION somewhere?
> 
> As far as I can see, sa11x0 completes frequency transition from within
> target() and so it does it synchronously.. And so it doesn't need to set
> CPUFREQ_ASYNC_NOTIFICATION...
> 
> Am I missing something?

The patch to which I'm replying removes the above calls.  These calls are
necessary to shutdown various bits of CPU-clock dependent hardware
before changing the CPU clock, and restore them - reconfiguring them
for the new clock rate after the transition has happened.

So, if you're removing these calls, what replaces them?  I don't see
anything which does without the above set.
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