Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support

From: Rafael J. Wysocki
Date: Tue Jul 11 2017 - 11:08:07 EST

On Tuesday, July 11, 2017 04:06:01 PM Dietmar Eggemann wrote:
> On 11/07/17 07:01, Viresh Kumar wrote:
> > On 10-07-17, 13:02, Dietmar Eggemann wrote:
> >> Yes, I will change this. The #define approach is not really necessary
> >> here since we're not in the scheduler hot-path and inlining is not
> >> really required here.
> >
> > It would be part of scheduler hot-path for the fast-switching case, isn't it ?
> > (I am not arguing against using weak functions, just wanted to correct above
> > statement).
> Yes you're right here.
> But in the meantime we're convinced that cpufreq_driver_fast_switch() is
> not the right place to call arch_set_freq_scale() since for (future)
> arm/arm64 fast-switch driver, the return value of
> cpufreq_driver->fast_switch() does not give us the information that the
> frequency value did actually change.
> So we probably have to do this soemwhere in the cpufreq driver(s) to
> support fast-switching until we have aperf/mperf like counters.

If that's the case, I'd say call arch_set_freq_scale() from drivers in all
cases or it will get *really* confusing.