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SubjectRe: [PATCH RFC v2 08/12] soc: samsung: pm_domain: Add support for parent power domain
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On Tue, Nov 25, 2014 at 9:57 AM, amit daniel kachhap
<amit.daniel@samsung.com> 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.

>>> 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.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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