linux-kernel - Re: [PATCH v4 1/4] regulator: helper routine to extract regulator_init

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Message-ID: <20111104223518.GC16978@opensource.wolfsonmicro.com>
Date:	Fri, 4 Nov 2011 22:35:19 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Olof Johansson <olof@...om.net>
Cc:	Rajendra Nayak <rnayak@...com>, grant.likely@...retlab.ca,
	patches@...aro.org, tony@...mide.com,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, lrg@...com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 1/4] regulator: helper routine to extract
 regulator_init_data

On Fri, Nov 04, 2011 at 03:16:12PM -0700, Olof Johansson wrote:
> On Fri, Nov 4, 2011 at 2:46 PM, Mark Brown

> >> Describing that in the device tree using regulator-specifiers
> >> shouldn't be too bad? The LDO will reference the DCDC as the parent
> >> supply (or input or whatever language you prefer). They don't have to
> >> be in the same topology, they will instead be under whatever
> >> controller/bus they are on for control -- i2c, etc.

> > That's not great as it means you've got a separate binding for supplies
> > that happen to be connected to another regulator from that used for
> > other supplies on the device which is particularly confusing in the
> > fairly common case where a regulator chip has multiple supplies.  Using
> > the same method for binding all supplies seems much neater.

> I'm not following the above 100%, but I think you are saying that you
> would prefer to describe the regulator / power hierarchy in the
> functional topology instead of how the various regulators and supplies
> are organized on i2c busses and other controllers?  And the obvious
> one that would be less than trivial to find a home for would be the
> top-level or freestanding fixed regulators that don't sit on a
> controlling bus.

No, that's not the issue at all.  The issue is that we want a single way
of describing the supplies a device has regardless of their function
(which is what the existing stuff does).

Consider the case of a simple regulator with register control.  It is
going to have a supply used for the regulator itself and almost
certainly also a separate digital buffer supply used to reference the
digital I/O.  It seems bad to specify the first supply in a different
manner to the second, and there are more complex examples where a supply
can be both a regulator input and also a more general purpose supply.
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