Re: [PATCH v6 10/10] soc: qcom: rpmhpd: Mark mx as a parent for cx

From: Stephen Boyd
Date: Wed Dec 12 2018 - 13:32:51 EST

Quoting Rajendra Nayak (2018-12-11 20:13:13)
> >>> Just to make sure there are no conflicting hierarchical constraints
> >>> between idle management and performance state management!?
> >>>
> >
> > I'm not sure what idle states mean to the CX and MX domains. Would it be
> > some sort of idle state governor attached at genpd creation time that
> > would adjust the main SoC power rails when all devices attached are
> > idle? Maybe I don't understand how idle states are different from
> > performance states.
> > My understanding is that devices using these domains would almost always
> > expect their clk frequency and clk on/off state to decide what the
> > performance state is, unless they need to ignore clk state because they
> > aren't managing clks and bump up the voltage directly when the device is
> > active. Either way, devices are actively managing the voltage they need
> > these voltage domains to operate at by using the genpd performance
> > states APIs.
> I am not quite sure whats the point that you are trying to make here,
> but this is what I would expect the users of these genpds to do,
> regardless of if they have a clk dependency or not.
> When the device is active, vote for a performance state they need
> then request for the genpd to be on. When they are idle, request for the
> genpd to be turned off.

I believe Ulf is asking because he's proposing to make genpd idle states
and genpd performance states orthogonal to each other. And to also make
performance states unaffected by the on/off state of the genpd.