On 11-08-21, 09:37, Quentin Perret wrote:

On Wednesday 11 Aug 2021 at 10:48:59 (+0530), Viresh Kumar wrote:

quoted

I had to use the pm-opp version, since almost everyone was using that.

On the other hand, there isn't a lot of OPP specific stuff in
dev_pm_opp_of_register_em(). It just uses dev_pm_opp_get_opp_count(),
that's all. This ended up in the OPP core, nothing else. Maybe we can
now move it back to the EM core and name it differently ?

Well it also uses dev_pm_opp_find_freq_ceil() and
dev_pm_opp_get_voltage(), so not sure how easy it will be to move, but
if it is possible no objection from me.

What uses these routines ? dev_pm_opp_of_register_em() ? I am not able
to see that at least :(

Right but the EM is a description of the hardware, so it seemed fair
to assume this wouldn't change across the lifetime of the OS, similar
to the DT which we can't reload at run-time. Yes it can be a little odd
if you load/unload your driver module, but note that you generally can't
load two completely different drivers on a single system. You'll just
load the same one again and the hardware hasn't changed in the meantime,
so the previously loaded EM will still be correct.

Yeah, it will be the same driver but a different version of it, which
may have updated the freq table. For me the EM is attached to the
freq-table, and the freq-table is not available anymore after the
driver is gone.

Anyway, I will leave that for you guys to decide :)

I hear your argument
about cpufreq driver development, but the locking involved to allow
'just' that is pretty involved, and nobody has complained about this
specific issue so far, so that didn't seem worth it. If we do have good
reasons to change the EM at runtime, then yes I think we should do it,
it just didn't seem like that was the case until now.

-- 
viresh

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek