linux-kernel - Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for power-domains

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Message-ID: <20170430124917.4m3d237pik7q47f3@sirena.org.uk>
Date:   Sun, 30 Apr 2017 21:49:17 +0900
From:   Mark Brown <broonie@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Rajendra Nayak <rnayak@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>, ulf.hansson@...aro.org,
        Kevin Hilman <khilman@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        robh+dt@...nel.org, lina.iyer@...aro.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for
 power-domains

On Thu, Apr 27, 2017 at 10:42:49AM +0100, Sudeep Holla wrote:
> On 26/04/17 14:55, Mark Brown wrote:

> > As I'm getting fed up of saying: if the values you are setting are not
> > voltages and do not behave like voltages then the hardware should not be
> > represented as a voltage regulator since if they are represented as
> > voltage regulators things will expect to be able to control them as
> > voltage regulators.  This hardware is quite clearly providing OPPs
> > directly, I would expect this to be handled in the OPP code somehow.

> I agree with you that we need to be absolutely sure on what it actually
> represents.

> But as more and more platform are pushing such power controls to
> dedicated M3 or similar processors, we need abstraction. Though we are
> controlling hardware, we do so indirectly. Since there were discussions
> around device tree representing hardware vs platform, I tend to think,
> we are moving towards platform(something similar to ACPI).

I don't think there's a meaningful hardware/platform distinction here -
in terms of what DT is describing the platform bit is just what the
hardware (the microcontrollers) happen to do, DT doesn't much care about
that though.

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