On Fri, Mar 16, 2012 at 12:36:35PM +0000, Arnd Bergmann wrote:

On Friday 16 March 2012, Linus Walleij wrote:

quoted

On Thu, Mar 15, 2012 at 9:58 PM, Arnd Bergmann [off-list ref] wrote:

quoted

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

quoted

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.

quoted

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.

quoted

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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