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

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Message-ID: <a1e3c706-9a8a-00b2-6ccb-08b95ee0b45b@gmail.com>
Date:   Thu, 24 Dec 2020 15:14:11 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
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

24.12.2020 09:51, Viresh Kumar пишет:
> 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.
> 

Alright, thank you.