On Tuesday 10 Aug 2021 at 14:25:15 (+0100), Lukasz Luba wrote:

The way I see this is that the flag in cpufreq avoids
mistakes potentially made by driver developer. It will automaticaly
register the *simple* EM model via dev_pm_opp_of_register_em() on behalf
of drivers (which is already done manually by drivers). The developer
would just set the flag similarly to CPUFREQ_IS_COOLING_DEV and be sure
it will register at the right time. Well tested flag approach should be
safer, easier to understand, maintain.

I would agree with all that if calling dev_pm_opp_of_register_em() was
complicated, but that is not really the case. I don't think we ever call
PM_OPP directly from cpufreq core ATM, which makes a lot of sense if you
consider PM_OPP arch-specific. I could understand that we might accept a
little 'violation' of the abstraction with this series if there were
real benefits, but I just don't see them.