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

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Date:   Tue, 8 Oct 2019 20:05:03 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-kernel@...r.kernel.org, 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()

08.10.2019 19:15, Mark Brown пишет:
> On Tue, Oct 08, 2019 at 06:02:36PM +0300, Dmitry Osipenko wrote:
> 
> Please fix your mail client to word wrap within paragraphs at something
> substantially less than 80 columns.  Doing this makes your messages much
> easier to read and reply to.

Indeed, thanks!

>> That OPP patch caused the same problem for the NVIDIA Tegra20 CPUFreq
>> driver (in-progress) and I resolved it in the coupler's code [0].
>> Perhaps the generic coupler could do the same thing by assuming that
>> min_uV=current_uV until any consumer sets the voltage, i.e. if
>> regulator_check_consumers(min_uV=0) returns min_uV=0.
> 
> That sounds like it might just postpone the inevitable - if you set the
> wrong voltage first it might decide to drop down some voltage that
> wasn't expected.  There's a bit of a bootstrapping issue.  I think it
> would be safer to just say that anything that is within spec won't get
> changed any time we balance, we'd only change things if needed to bring
> them back into spec.

Yes, the case of changing voltage before regulator is enabled seems
won't work as expected.

Maybe it won't hurt to disallow a non always-on regulators to be coupled
until there will be a real user for that case.