linux-kernel - Re: [PATCH v2 28/48] soc/tegra: Introduce core power domain driver

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Date:   Thu, 24 Dec 2020 12:21:42 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 28/48] soc/tegra: Introduce core power domain driver

On 23-12-20, 23:37, Dmitry Osipenko wrote:
> 23.12.2020 08:57, Viresh Kumar пишет:
> > What's wrong with getting the regulator in the driver as well ? Apart from the
> > OPP core ?
> 
> The voltage syncing should be done for each consumer regulator
> individually [1].
> 
> Secondly, regulator core doesn't work well today if the same regulator
> is requested more than one time for the same device.

Hmm...

> >> will return the OPP table regulator in order to allow driver to use the
> >> regulator directly. But I'm not sure whether this is a much better
> >> option than the opp_sync_regulators() and opp_set_voltage() APIs.
> > 
> > set_voltage() is still fine as there is some data that the OPP core has, but
> > sync_regulator() has nothing to do with OPP core.
> > 
> > And this may lead to more wrapper helpers in the OPP core, which I am afraid of.
> > And so even if it is not the best, I would like the OPP core to provide the data
> > and not get into this. Ofcourse there is an exception to this, opp_set_rate.
> > 
> 
> The regulator_sync_voltage() should be invoked only if voltage was
> changed previously [1].
> 
> The OPP core already has the info about whether voltage was changed and
> it provides the necessary locking for both set_voltage() and
> sync_regulator(). Perhaps I'll need to duplicate that functionality in
> the PD driver, instead of making it all generic and re-usable by other
> drivers.
> 
> [1]
> https://elixir.bootlin.com/linux/v5.10.2/source/drivers/regulator/core.c#L4107

Lets do it in the OPP core and see where we go.

-- 
viresh