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

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Message-ID: <20140205181817.GG32298@sirena.org.uk>
Date:	Wed, 5 Feb 2014 18:18:17 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Bjorn Andersson <bjorn@...o.se>
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 Wed, Feb 05, 2014 at 10:00:15AM -0800, Bjorn Andersson wrote:
> On Tue, Feb 4, 2014 at 12:00 PM, Mark Brown <broonie@...nel.org> wrote:

> > So we should be changing the code to allow a set_voltage() that sets the
> > voltage to the existing voltage regardless of constraints allowing a
> > change then - that's what the underlying issue is.  Your change wouldn't
> > cover the case where the hardware defualt is being used for example.

> Makes sense, but the only thing we could check for would be if min_uV
> == max_uV == current-voltage. That would work out fine for this use
> case, but do you think it would be good enough?

It should be fine to check for min_uV <= current-voltage <= max_uV
instead if CHANGE_VOLTAGE isn't available, so long as the existing
setting is in the range it's fine.

> The best thing I've come up with then is to add the following check in
> regulator_set_voltage().

> if (min_uV == max_uV && _regulator_get_voltage(rdev) == min_uV)
>     goto out;

> Would this be acceptable? It's achieving the same thing as my patch,
> is more robust and covers the case of setting the voltage to the hw
> default value.

That sort of thing yes, just short circuit out the main logic in this
case.

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