Re: [RFC 2/2] ARM:Tegra: Device Tree Support: Initialize audio card gpio's from the device tree.

[Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>]

On Mon, May 30, 2011 at 04:49:09PM -0700, Olof Johansson wrote:

> What I was not sure about was the use of having an array of unnamed
> gpios as part of the consumer-side binding, where there's no logical
> ordering between these entries.

> In the sdhci case, there are three gpios; one to supply power to the slot;
> one for card detect and one for write protect sense.

> In that case, it would make a whole lot more sense to have three separate
> properties, say "power-gpio", "cd-gpio" and "wp-gpio", than an opaque array of
> entries without description besides what comments are used in the dts file.

> That these in turn point just to gpio number <x> at controller <y> is OK with
> me. Also, I can see cases where it makes sense to have more than one gpio
> references in a property (i.e. busses), but only where there's either internal
> ordering to them, or where ordering doesn't matter at all.

I agree strongly with this - there's a very good reason why this is the
existing pattern for platform data.  There's other cases that are even
worse than SDHCI where you can get a large number of potential outputs
from a device that could be wired up, a vanishingly small number
(possibly even none) of which will actually be used in a given system.