linux-kernel - Re: [PATCH v3] regulator: treat regulators with constant volatage as fixed

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Date:	Tue, 20 Nov 2012 14:20:20 +0100
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Liam Girdwood <lrg@...com>, Chris Ball <cjb@...top.org>
Subject: Re: [PATCH v3] regulator: treat regulators with constant volatage as
 fixed

Hello,

On 11/14/2012 3:01 AM, Mark Brown wrote:
> On Tue, Nov 13, 2012 at 10:49:37AM +0100, Marek Szyprowski wrote:
>
> > +	if (rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_VOLTAGE) {
> > +		if (rdev->desc->n_voltages)
> > +			return rdev->desc->n_voltages;
> > +		else
> > +			return -EINVAL;
> > +	} else {
> > +		return 1;
> > +	}
>
> Hrm, now I can read the logic I'm not convinced this is a good idea.
> This will report that we have an available voltage for devices which
> don't know their voltage (things like battery supplies often do this as
> the voltage is unregulated) and it will mean that we are doing something
> different for the case where there's only one voltage (reporting the
> restricted count instead of the physically supported count).
>
> I think we want a regulator_can_change_voltage() or possibly a count
> function (though I can't see any use cases except this) which answers
> the question directly instead of layering on top of this function.

Right, regulator_can_change_voltage() sounds much better than my hacky
approach. The first client would be probably sdhci/mmc driver, as
'can_change_voltage' check sounds much more appropriate than counting
available voltage values.

I will prepare patches soon.

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center


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