Re: [PATCH V2 0/2] PM / Domains / OPP: Introduce domain-performance-state binding

Rob Herring
2016-12-22T18:14:22Z

On Mon, Dec 12, 2016 at 04:26:17PM +0530, Viresh Kumar wrote:
> Hello,
>
> Some platforms have the capability to configure the performance state of
> their Power Domains. The performance levels are represented by positive
> integer values, a lower value represents lower performance state.
>
> We had some discussions about it in the past on the PM list [1], which is
> followed by discussions during the LPC. The outcome of all that was that we
> should extend Power Domain framework to support active state power management
> as well.
>
> The power-domains until now were only concentrating on the idle state
> management of the device and this needs to change in order to reuse the
> infrastructure of power domains for active state management.

>From a h/w perspective, are idle states really different from
performance states?

>
> To get a complete picture of the proposed plan, following is what we
> need to do:
> - Create DT bindings to get domain performance state information for the
> platforms.

I would do this last so you can evolve things if you're not certain
about what the bindings should look like. You can always start with
things in the kernel and add to DT later.

While in theory we should be able to just "describe the h/w" in DT and
develop the Linux side independently, this feels too much like the
bindings are just evolving with Linux needs.

Rob