Re: mixing SCMI and PSCI power domain hierarchy

[Kevin Hilman <khilman@baylibre.com>]

Ulf Hansson <ulf.hansson@linaro.org> writes:

> On Fri, 25 Apr 2025 at 16:39, Kevin Hilman <khilman@baylibre.com> wrote:
>>
>> Ulf Hansson <ulf.hansson@linaro.org> writes:
>>
>> [...]
>>
>> >> Anyways, curious what you think.  I quite like this solution because it
>> >> solves two fairly big limitations in the SCMI PM domain implementaion
>> >> that exist today with one relatively simple solution.
>> >
>> > Well, I am not the one to convince in regards to DT bindings. Putting
>> > the DT bindings aside, I think your extensions for the SCMI Power
>> > Domain to support parent-domains makes perfect sense to me!
>> >
>> > In regards to the DT bindings (again, I am not the expert here), but
>> > maybe we could try to extend the current way we describe parent
>> > domains instead of inventing something entirely new. Could the below
>> > work?
>> >
>> > scmi_pds: protocol@11 {
>> >         reg = <0x11>;
>> >          #power-domain-cells = <1>;
>> >          power-domains = <&MAIN_PD>, <&WKUP_PD>; // a list of phandles
>> >          power-domains-child-ids = <15>, <19> ; // a list of indexes
>> > corresponding to the list of phandles above
>>
>> Yeah, this is probably better.  I'm not crazy about introducing novel
>> DT bindings either.  I will make a PoC of this approach.
>>
>> The catch with either approach is that it will be a long list.  e.g. on
>> the TI AM62L, there are 50+ SCMI IDs.
>
> Just wanted to share a brief update. I got the opportunity to chat
> with Krzysztof and Abel at Linaro Connect this week, about extending
> the power-domain DT bindings, in the way I proposed above. We agreed
> that it seems like a reasonable approach.

OK, great.  Thanks!

I just posted an RFC with an initial implementation:
https://lore.kernel.org/linux-pm/20250528-pmdomain-hierarchy-onecell-v1-1-851780700c68@baylibre.com/T/#u

Kevin