linux-kernel - Re: [PATCH v3 05/12] opp: Add dev_pm_opp_set

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Message-ID: <a48dca91-4264-e153-cefa-ccbcca1b1d9d@gmail.com>
Date:   Mon, 18 Jan 2021 22:14:28 +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>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        "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>, Nishanth Menon <nm@...com>,
        Yangtao Li <tiny.windzz@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 05/12] opp: Add dev_pm_opp_set_voltage()

18.01.2021 12:52, Viresh Kumar пишет:
> On 18-01-21, 03:55, Dmitry Osipenko wrote:
>> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
>> index 99d18befc209..341484d58e6c 100644
>> --- a/drivers/opp/core.c
>> +++ b/drivers/opp/core.c
>> @@ -2731,3 +2731,58 @@ int dev_pm_opp_sync_regulators(struct device *dev)
>>  	return ret;
>>  }
>>  EXPORT_SYMBOL_GPL(dev_pm_opp_sync_regulators);
>> +
>> +/**
>> + * dev_pm_opp_set_voltage() - Change voltage of regulators
>> + * @dev:	device for which we do this operation
>> + * @opp:	opp based on which the voltages are to be configured
>> + *
>> + * Change voltage of the OPP table regulators.
>> + *
>> + * Return: 0 on success or a negative error value.
>> + */
>> +int dev_pm_opp_set_voltage(struct device *dev, struct dev_pm_opp *opp)
> 
> I think we should do better than this, will require some work from
> your part though (or I can do it if you want).
> 
> Basically what you wanted to do here is set the OPP for a device and
> this means do whatever is required for setting the OPP. It is normally
> frequency, which is not your case, but it is other things as well.
> Like setting multiple regulators, bandwidth, required-opps, etc.
> 
> I feel the right way of doing this would be to do this:
> 
> Factor out dev_pm_opp_set_opp() from dev_pm_opp_set_rate() and make
> the later call the former. And then we can just call
> dev_pm_opp_set_opp() from your usecase. This will make sure we have a
> single code path for all the set-opp stuff. What do you think ?
> 

Sounds like it could be a lot of code moving and some extra complexity
will be added to the code. If nobody will ever need the universal
dev_pm_opp_set_opp(), then it could become a wasted effort. I'd choose
the easiest path, i.e. to defer the dev_pm_opp_set_opp() implementation
until somebody will really need it.

But if it looks to you that it won't be a too much effort, then I'll
appreciate if you could type the patch.