Re: [PATCH v2 3/4] cpufreq: mediatek: add Mediatek cpufreq driver

From: Viresh Kumar <viresh.kumar@linaro.org>
To: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Chen Fan <fan.chen@mediatek.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Howard Chen <ibanezchen@gmail.com>,
	"Joe.C" <yingjoe.chen@mediatek.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
	Pawel Moll <pawel.moll@arm.com>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Rob Herring <robh+dt@kernel.org>,
	linux-mediatek@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Eddie Huang <eddie.huang@mediatek.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Kumar Gala <galak@codeaurora.org>
Subject: Re: [PATCH v2 3/4] cpufreq: mediatek: add Mediatek cpufreq driver
Date: Wed, 11 Mar 2015 16:33:49 +0530	[thread overview]
Message-ID: <CAKohpom4riOhzc3hK8B2tiSwGx0zG96C7QNeQB0yZaPMd_OpLw@mail.gmail.com> (raw)
In-Reply-To: <20150311105307.GW28806@sirena.org.uk>

On 11 March 2015 at 16:23, Mark Brown <broonie@kernel.org> wrote:
> On Tue, Mar 10, 2015 at 08:20:43AM +0530, Viresh Kumar wrote:
>
> Please don't send upstream e-mail to my work account, I use this address
> pretty consistently for upstream.  Upstream mail to my work account
> frequently ends up unread.

Sorry about that, I did exactly opposite of this earlier :(

>> On 6 March 2015 at 11:19, Pi-Cheng Chen <pi-cheng.chen@linaro.org> wrote:
>> > On 5 March 2015 at 17:55, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
>> > About putting
>> > those stuff into regulator driver, I think you mean creating a
>> > "virtual regulator
>> > device" and put all the voltage controlling complex into the driver, right?
>> > Maybe it's a good idea in this case, but I am sure if this kind of
>> > virtual regulator is acceptable.
>
>> @Mark: Is this allowed to create virtual regulator for a CPU ?
>
> I don't really know what the above means or what problem it's supposed
> to solve.

On mediatek platform, they need to configure two regulators in order to change
DVFS state of the big cluster. The generic cpufreq-dt driver and earlier OPP
bindings have support for a single regulator only and so what Pi-cheng tried
to do is,
- Configure one of the regulators using cpufreq-dt
- And other one using cpufreq frequency change notifiers

This looks awkward..

What I suggested was to create another virtual regulator for CPU which will
eventually configure both the regulators. And so the question that such
virtual regulators are allowed or not.