On 01-03-17, 09:45, Geert Uytterhoeven wrote:

On Wed, Mar 1, 2017 at 7:14 AM, Viresh Kumar [off-list ref] wrote:

quoted

On 28-02-17, 09:52, Rob Herring wrote:

quoted

On Tue, Feb 28, 2017 at 9:14 AM, Ulf Hansson [off-list ref] wrote:

quoted

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.

As clock domains (and their support code) are fairly orthogonal to power
areas, currently our power area controller driver just forwards the
clock handling
to the clock driver (cfr. rcar-sysc).

Perhaps Rajendra can explain better but Qcom have a case where they need to
program two power domains as well.

-- 
viresh