[PATCH 1/3] PM: domains: Drop the performance state vote for a device at detach

[Dmitry Osipenko]

07.09.2021 13:16, Ulf Hansson пишет:
...
>>> Also note that a very similar problem exists, *before* the device gets
>>> attached in the first place. More precisely, nothing prevents the
>>> performance state from being set to a non-compatible value for an
>>> always-on HW/device that hasn't been attached yet. So maybe you need
>>> to set the maximum performance state at genpd initializations, then
>>> use the ->sync_state() callback to very that all consumers have been
>>> attached to the genpd provider, before allowing the state to be
>>> changed/lowered?
>>
>> That is already done by the PD driver.
>>
>> https://elixir.bootlin.com/linux/latest/source/drivers/soc/tegra/pmc.c#L3790
> 
> Yes, I already knew that, but forgot it. :-) Thanks for the pointer.
> Let me rethink the approach.
> 
> In a way, it kind of sounds like this is a generic problem - so
> perhaps we should think of adding a ->withdraw_sync_state() callback
> that can be assigned by provider drivers, to get informed when a
> consumer driver is getting unbinded.

Not sure, doesn't feel to me that this is necessary for today. A bit too
cumbersome for a simple sanity-check, IMO.