linux-kernel - Re: [PATCH] regulator: core: Make regulator object reflect configured voltage

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Message-ID: <CAJAp7OjCnJ=P9Gi20=D9gybREiSaqd1CaQ0K=9fGbCzU1gTFLw@mail.gmail.com>
Date:	Tue, 4 Feb 2014 10:02:14 -0800
From:	Bjorn Andersson <bjorn@...o.se>
To:	Mark Brown <broonie@...nel.org>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] regulator: core: Make regulator object reflect configured voltage

On Tue, Feb 4, 2014 at 3:05 AM, Mark Brown <broonie@...nel.org> wrote:
> On Mon, Feb 03, 2014 at 09:54:28PM -0800, Bjorn Andersson wrote:
>
>> +     /*
>> +      * Make the regulator reflect the configured voltage selected in
>> +      * machine_constraints_voltage()
>> +      */
>> +     if (rdev->constraints->apply_uV &&
>> +         rdev->constraints->min_uV == rdev->constraints->max_uV) {
>> +             regulator->min_uV = rdev->constraints->min_uV;
>> +             regulator->max_uV = rdev->constraints->min_uV;
>> +     }
>> +
>
> Why not do this at the time we apply the voltage?  That would seem to be
> more robust, doing it in a separate place means that we might update one
> bit of code and not the other or might change the execution path so that
> one gets run and the other doesn't.

I do share your concerns about having this logic mirrored here is
risky, unfortunately the regulator object is created upon request from
a consumer; so it is not available when regulator_register() calls
set_machine_constraints().

An alternative is to drop the conditional setting of
REGULATOR_CHANGE_VOLTAGE from of_regulator.c and force the regulator
drivers to set this flag explicitly; to avoid the difference in
behavior depending on configuration.

Regards,
Bjorn
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