Re: [RFC][PATCH v3 1/3] runtime interpreted power sequences

[Alex Courbot]

On Fri 03 Aug 2012 03:11:12 AM JST, Mark Brown wrote:
> On Thu, Aug 02, 2012 at 10:21:57AM +0200, Thierry Reding wrote:
> > On Thu, Aug 02, 2012 at 05:00:13PM +0900, Alex Courbot wrote:
>
> > > The problem is, how do we turn these phandles into the resource of
> > > interest. The type of the resource can be infered by the name of the
> > > property. The hard part is resolving the resource from the phandle -
> > > it seems like the API just does not allow to do this. GPIO has
> > > of_get_named_gpio, but AFAIK there are no equivalent for regulator
> > > consumer and PWM: the only way to use the DT with them is through
> > > get_regulator and get_pwm which work at the device level.
>
> > > Or is there a way that I overlooked?
>
> > No, you are right. Perhaps we should add exported functions that do the
> > equivalent of of_pwm_request() or the regulator_dev_lookup() and
> > of_get_regulator() pair.
>
> I missed some of the earlier bits of the thread here but why can't we do
> device based lookups?

That is because the phandles would not be properties of the device node 
but rather of its sub-nodes:

backlight {
    compatible = "pwm-backlight";
    ...
    power-on-sequence {
        step@0 {
            regulator = <&backlight_reg>;
            enable;
        };


So here simply using regulator_get on the backlight device would not work.

Alex.
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