linux-kernel - Re: [PATCH v6 1/1] mfd: arizona: Export functions to control subsystem DVFS

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Message-ID: <20150526154515.GB26432@opensource.wolfsonmicro.com>
Date:	Tue, 26 May 2015 16:45:15 +0100
From:	Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH v6 1/1] mfd: arizona: Export functions to control
	subsystem DVFS

On Tue, May 26, 2015 at 04:29:42PM +0100, Mark Brown wrote:
> On Tue, May 26, 2015 at 02:52:05PM +0100, Lee Jones wrote:
> 
> > Shouldn't this DVFS dump live in drivers/cpufreq?
> 
> cpufreq is specifically for CPUs (with the governors and everything) and
> has its own problems here.  There is devfreq which was crated for this
> sort of thing (though more on a SoC level) though, not sure if it's a
> good fit or not.

The only codecs that have DVFS are WM8997, WM8998 and WM5102. No newer
codecs have it so it feels like unnecessary effort to create a whole
new driver for these three codecs. In any case, all we're really doing
here is setting the state of a single bit which tells the codec whether
we're feeding it enough DCVDD for it to do its internal DVFS. Most of
the additional complexity here is around co-operating with the
runtime_suspend/resume code in the MFD driver,
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