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

[Arnd Bergmann <arnd@arndb.de>]

On Friday 16 March 2012, Linus Walleij wrote:
> On Thu, Mar 15, 2012 at 9:58 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > [Per]
> >> The stedma40 filter function is not really specific for ux500. ux500
> >> use stedma40 but it should be possible to replace this DMA.IP with
> >> some other DMA-controller. This is board specific configuration. You
> >> should not need to change the mmci-driver just because the dma-driver
> >> has changed, right?
> >> Or will the board-configuration now be placed in mmci-ux500?
> >
> > Right, the DMA configuration does not really belong in there, but
> > the voltage setup might (unless we convert that to the regulator
> > setup).
> 
> The voltage to power the card is already using the regulator
> framework with the MMC-specific helpers in the MMCI driver.
> 
> 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.

> 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.

	Arnd