Re: [PATCH 0/5] MMC: mmci: Provide bindings for Device Tree

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

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On Fri, Mar 16, 2012 at 12:36:35PM +0000, Arnd Bergmann wrote:
> On Friday 16 March 2012, Linus Walleij wrote:
> > On Thu, Mar 15, 2012 at 9:58 PM, Arnd Bergmann <arnd@arndb.de> wrote:

> > But I guess you're after modelling the levelshifter as a regulator?

> > Basically the level shifter is a separate device has two voltage
> > inputs A and B (from other regulators) that is controlled by a
> > simple GPIO to select voltage A or B to drive the signals to
> > the card.

> > That could probably be modelled as a regulator with two
> > volategs for sure, but then we should maybe create a more
> > generic "struct level_shifter_regulator" (or whatever) for the
> > concept as a whole.

> Ok, thanks for the explanation.

I'm not sure I'd bother defining a special regulator type for this if it
is done using regulators - given that it's likely to just be a GPIO
rather than a specific driver I'm not sure it's worth worrying about how
exactly the hardware is implemented.

> > Let's page Mark about what to do with levelshifters and whether
> > they are regulators of sorts in his book.

> It does sound appealing, especially because this one could be
> done completely generically by defining a regulator that has
> a bunch of other regulators as well as a set of gpio lines as
> inputs and one output that can be used in other devices. We
> would probably only use this one together with device tree then.

It seems sensible to me - probably the existing gpio-regulator driver
can do the job, though it's not unreasonable to expect that we'll want
to support switching between variable voltage supplies at some point.

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