Re: [PATCH v3 1/3] PM: domains: Make set_performance_state() callback optional

From: Viresh Kumar
Date: Tue Jan 19 2021 - 05:26:07 EST

On 19-01-21, 10:52, Ulf Hansson wrote:
> That would work if the topology is built from top to bottom, but I
> don't think we can rely on that.
> For example, when a domain A is added as a child to domain B, domain B
> doesn't have a parent yet (and the "can-handle-pstates" don't get set
> for neither domain A or domain B). Next, domain B is added as child
> domain to domain C. Domain C has the "can-handle-pstates" set, which
> means domain B gets the "can-handle-pstates" set as well. This means
> domain A, will not have "can-handle-pstates" set, while it probably
> should have.

Okay, I missed that part.

> >
> > > So, maybe we should simply just stick to the existing code, forcing
> > > the parent to have a ->set_performance() callback assigned if
> > > propagation should continue?
> >
> > I think it would be better to fix the issue even if we aren't fully optimized
> > and making the change to make sure we keep propagating is rather important.
> Alright, let's continue with Dmitry's patches and discuss this further
> when v4 is out, as he seems to have it almost ready.