On Wednesday 11 Aug 2021 at 14:43:21 (+0530), Viresh Kumar wrote:

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

quoted

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 :(

Yep, it's not immediately obvious, but see how it sets the struct
em_data_callback to point at _get_power() where the actual energy
calculation is done. So strictly speaking _get_power() is what uses
these routines, but it goes in hand with dev_pm_opp_of_register_em() so
I guess the same reasoning applies.

quoted

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 :)

IIUC Lukasz is working on something that should allow changing the EM at
run-time, so hopefully it'll enable this use-case as well, but we'll see :)

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