Re: [PATCH V3 2/7] PM / OPP: Introduce "domain-performance-state" binding to OPP nodes

From: Viresh Kumar
Date: Wed Mar 01 2017 - 01:14:28 EST


On 28-02-17, 09:52, Rob Herring wrote:
> On Tue, Feb 28, 2017 at 9:14 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> > This comes from the early design of the generic PM domain, thus I
> > assume we have some HW with such complex PM topology. However, I don't
> > know if it is actually being used.
> >
> > Moreover, the corresponding DT bindings for "power-domains" parents,
> > can easily be extended to cover more than one parent. See more in
> > Documentation/devicetree/bindings/power/power_domain.txt
>
> I could easily see device having 2 power domains. For example a cpu
> may have separate domains for RAM/caches and logic.

An important thing here is that PM domain doesn't support such devices. i.e. a
device isn't allowed to have multiple PM domains today. So a way to support such
devices can be to create a virtual PM domain, that has two parents and device as
its child.

--
viresh