linux-kernel - Re: [patch/rfc 2.6.29-rc6 1/2] regulator: enumerate voltages

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Message-Id: <200902251547.53256.david-b@pacbell.net>
Date:	Wed, 25 Feb 2009 15:47:52 -0800
From:	David Brownell <david-b@...bell.net>
To:	Mark Brown <broonie@...ena.org.uk>
Cc:	Liam Girdwood <lrg@...mlogic.co.uk>,
	lkml <linux-kernel@...r.kernel.org>,
	OMAP <linux-omap@...r.kernel.org>
Subject: Re: [patch/rfc 2.6.29-rc6 1/2] regulator: enumerate voltages

On Wednesday 25 February 2009, Mark Brown wrote:
> >       get_voltage() {
> >               read selector from hardware
> >               map selector to voltage
> >               return that voltage
> >       }
> 
> > So it's trivial for similar code to take the selector as
> > a function parameter, and do the same thing.  Repackage
> > the existing code a bit; bzzt, done!
> 
> Yes, that's a reasonable point (though I'd still like to see the maximum
> turn into a static value now I think about it).

At the regulator_desc level, that's trivial; I'll do that
in the patch you'll see.

In terms of the consumer interface, not -- "struct regulator"
is opaque to consumers, and everything is a functional accessor.
So I'll leave that as-is.


> > It will be fairly common for the regulator to support voltages
> > that are disallowed by the machine constraints, though.  That
> > can produce "holes" too; and not necessarily only for the lowest
> > or highest selector codes.
>
> At present only continous ranges are possible, though.  I can't think of
> any systems I've seen that'd want discontinous constraints, though I'm
> sure there are some.

Consider a regulator where voltage selectors 0..3 correspond to
voltages

	{ 3.3V, 1.8V, 4.2V, 5.0V }

With machine constraints that say voltages go from 3V to 4.5V ...

- Dave
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