Re: [PATCH v2 2/2] [RFC] CPUFreq: Add support for cpu-perf-dependencies

Viresh Kumar
2020-10-09T11:17:18Z

On 09-10-20, 12:10, Nicola Mazzucato wrote:
> I thought about it and looked for other platforms' DT to see if can reuse
> existing opp information. Unfortunately I don't think it is optimal. The reason
> being that, because cpus have the same opp table it does not necessarily mean
> that they share a clock wire. It just tells us that they have the same
> capabilities (literally just tells us they have the same V/f op points).

No.

> Unless I am missing something?

Yes.

Here are the different scenarios which can happen.
- Two CPUs have separate OPP tables, even if they are exact copy of
each other, these CPUs don't share a clock line, but just v/f points
as you said.

- Two CPUs use the same OPP table, i.e. both point to it, but
"opp-shared" property is missing. This is same as above case. They
just share the v/f points and this is the preferred way instead of
duplicate OPP tables.

- Case two with "opp-shared" property present in the OPP table. The
CPUs share clock-lines.

And this is exactly how we find out today if CPUs share a policy or
not.

--
viresh