linux-kernel - Re: [PATCH 6/6 v6] cpufreq, highbank: add support for highbank cpufreq

Open Source and information security mailing list archives

Date:	Wed, 28 Nov 2012 08:01:15 -0800
From:	Mike Turquette <mturquette@...com>
To:	Shawn Guo <shawn.guo@...aro.org>,
	Mark Langsdorf <mark.langsdorf@...xeda.com>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 6/6 v6] cpufreq, highbank: add support for highbank cpufreq

Quoting Shawn Guo (2012-11-28 07:17:44)
> On Wed, Nov 28, 2012 at 10:58:02PM +0800, Shawn Guo wrote:
> > On Wed, Nov 28, 2012 at 07:16:12AM -0600, Mark Langsdorf wrote:
> > > I'd
> > > have to move most of the logic of hb_set_target() into
> > > clk_highbank.c:clk_pll_set_rate() and then add extra logic for when
> > > cpufreq is not enabled/loaded.
> > 
> > You only need to move hb_voltage_change() into cpu clock's .set_rate()
> > hook with no need of checking if cpufreq is enabled or not.
> > 
> Need to also check whether frequency or voltage should be changed first
> in .set_rate() though.
> 
> Shawn
> 

The notifiers in the clk framework might be a better place for this than
just simply hacking the logic into the .set_rate callback.

I haven't looked at the definition of hb_voltage_change but does the
call graph make any clk api calls?  Are you talking over i2c to a
regulator?  If so then you'll probably hit the same reentrancy problem I
hit when trying to make a general solution.

Regards,
Mike

> 
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