linux-kernel - Re: [PATCH] regulator: do not balance regulators without constraints

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Message-ID: <20200529111031.GI4610@sirena.org.uk>
Date:   Fri, 29 May 2020 12:10:31 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Dmitry Osipenko <digetx@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>, peron.clem@...il.com,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        linux-samsung-soc@...r.kernel.org,
        Chanwoo Choi <cw00.choi@...sung.com>
Subject: Re: [PATCH] regulator: do not balance regulators without constraints

On Fri, May 29, 2020 at 07:45:06AM +0200, Marek Szyprowski wrote:
> On 28.05.2020 15:43, Mark Brown wrote:

> > This forces every supply to have something which explicitly manages
> > voltages which means that if one of the coupled supplies doesn't really
> > care about the voltage (perhaps doesn't even have any explicit
> > consumers) and just needs to be within a certain range of another supply
> > then it'll end up restricting things needlessly.

> Frankly, that's exactly what we need for Exynos5422 case. If devfreq 
> driver is not enabled/compiled, we want to keep the "vdd_int" volatage 
> unchanged. This confirms me that we really need to have a custom coupler 
> for Exynos5422 case. It will solve such issues without adding hacks to 
> regulator core.

It sounds like you need that or some form of cooperation between the
devfreq and cpufreq drivers.

> > Saravana was trying to do some stuff with sync_state() which might be
> > interesting here although I have concerns with that approach too:

> >     https://lore.kernel.org/lkml/20200527074057.246606-1-saravanak@google.com/

> This still doesn't solve the above mentioned case.

I didn't mean the particular patch, I meant something using the
sync_state() callback.

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