linux-kernel - Re: [PATCH] regulator: core: Skip balancing of the enabled regulators in regulator

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Message-ID: <20191008154844.GM4382@sirena.co.uk>
Date:   Tue, 8 Oct 2019 16:48:44 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-kernel@...r.kernel.org, Dmitry Osipenko <digetx@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-samsung-soc@...r.kernel.org,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Kamil Konieczny <k.konieczny@...sung.com>
Subject: Re: [PATCH] regulator: core: Skip balancing of the enabled
 regulators in regulator_enable()

On Tue, Oct 08, 2019 at 03:24:17PM +0200, Bartlomiej Zolnierkiewicz wrote:

> Commit 7f93ff73f7c8 ("opp: core: add regulators enable and disable")
> currently can be safely reverted as all affected users use always-on
> regulators. However IMHO it should be possible to enable always-on
> regulator without side-effects.

With coupled regulators you might have something kicking in because a
change was made on a completely different regulator...  If we don't take
account of coupling requirements we'd doubtless have issues with that at
some point.

> When it comes to setting regulator constraints before doing enable
> operation, it also seems to be possible solution but would require
> splitting regulator_set_voltage() operation on two functions:

> - one for setting constraints (before regulator_enable() operation)

> - the other one actually setting voltage (after enable operation)

I don't follow?  What would a "constraint" be in this context and how
would it be different to the voltage range you'd set in normal operation?

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