PM: allow custom policy to use default policy code without duplication

[nashif]

• pm: split default policy so custom code can call it
• doc: pm: do not hide pm_policy_next_state

[ceolin]

Hmm mixed feelings about it, this can be helpful but it is one more indirection, one more api and possibly can cause confusion ... I would just make the API public and let the application completely define their policy, which can probably be the default with slightly changes.

[nashif]

I would just make the API public and let the application completely define their policy, which can probably be the default with slightly changes.

what API? It is already public.

the idea here is that you might end up duplicating the code of the default policy in your app, why not just call the implementation directly and not having to reimplement it?

const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
{

       /* custom policy code here */
       ....
       ....
       ....
       /* end custom policy */
       return pm_policy_default_next_state(cpu, ticks);
}

[ceolin]

I would just make the API public and let the application completely define their policy, which can probably be the default with slightly changes.

what API? It is already public.

I mean't not hidden this API.

the idea here is that you might end up duplicating the code of the default policy in your app, why not just call the implementation directly and not having to reimplement it?

I see the reason, I just don't now if that is common case and consequently worth having one more function and this indirection. That's useful in #61726 the way it was proposed, but if they are defining their own policy they may remove things like power state constraints and latency constraints if they are not using and making it faster / simpler ...

Not a blocker though.

I would just make the API public and let the application completely define their policy, which can probably be the default with slightly changes.

const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
{

       /* custom policy code here */
       ....
       ....
       ....
       /* end custom policy */
       return pm_policy_default_next_state(cpu, ticks);
}