Re: [PATCH RFC v2 08/12] soc: samsung: pm_domain: Add support for parent power domain

[Marek Szyprowski]

Hello,

On 2014-11-25 10:19, Geert Uytterhoeven wrote:
> On Tue, Nov 25, 2014 at 9:57 AM, amit daniel kachhap
> <amit.daniel@xxxxxxxxxxx>  wrote:
> > > > diff --git a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
> > > > index 00ebda1..0160bdc 100644
> > > > --- a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
> > > > +++ b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
> > > > @@ -24,6 +24,7 @@ Optional Properties:
> > > >          - pclkN, clkN: Pairs of parent of input clock and input clock to the
> > > >                  devices in this power domain. Maximum of 4 pairs (N = 0 to 3)
> > > >                  are supported currently.
> > > > +- parents: phandle of parent power domains.
> Why not using just "power-domains = <&pd_top>"?
> This is consistent with how clocks refer to their parent clocks.

I agree. The only question is weather exynos dts should keep using 
samsung,power-domain
property, or switch to generic 'power-domains' approach. I assume that 
exynos-pm driver
should support both.

> > > >   Node of a device using power domains must have a samsung,power-domain property
> > > >   defined with a phandle to respective power domain.
> > > > @@ -48,6 +49,7 @@ Example:
> > > >          mfc_pd: power-domain@10044060 {
> > > >                  compatible = "samsung,exynos4210-pd", "samsung,exynos7-pd-mfc";
> > > >                  reg = <0x10044060 0x20>;
> > > > +               parents = <&pd_top>;
> > > >                  #power-domain-cells = <0>;
> > > >          };
> > > This seems like a good and generic approach to describe that a PM
> > > domain could have a parent. I would suggest to rename it, such it
> > > reflects its a PM domain binding though.
> > I am not sure if this is generic. I guess PD's represented like below
> > are more generic.
> > PD1 {
> >          PD2 {
> >                  PD3 {
> >                  };
> >          };
> > };
> Such a representation is not always possible.
> If you have one power-controller for a hierarchy of PM domains, you can
> use it.
> If you have multiple power-controllers, the power controller nodes are at the
> same level in DT, so you'll have to use "power-domains" properties to link
> them together.

I agree. I will send updated patch for this purpose for existing exynos4 
power domain driver.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/