Re: [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain

Dmitry Osipenko
2021-10-07T10:36:57Z

07.10.2021 12:18, Ulf Hansson пишет:
>> Please let me iterate once again. The problem we currently have is that
>> clock may be enabled during NOIRQ time. In order to enable clock, it
>> needs to be prepared. In order to prepare clock, the clock's device
>> needs to be runtime-resumed. The runtime PM is unavailable at the NOIRQ
>> time.
>>
>> To solve this problem we need to prepare clock beforehand.
>>
>> The clock will stay prepared during suspend, but this is not a problem
>> since all the clocks we care about don't require high voltage and
>> voltage is guaranteed to be bumped high during suspend by Tegra's
>> regulator-coupler driver anyways.
>>
>> So everything we need to do is to keep clocks prepared. There are two
>> options how to do that:
>>
>> [1] this patch which explicitly prepares clocks using clk API.
>>
>> [2] Use runtime PM API, like this:
>>
>> static const struct dev_pm_ops tegra_clock_pm = {
>> SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_resume_and_get, pm_runtime_put)
>> };
>>
>> Ulf, are you now okay with the current variant [1] of the patch or you
>> prefer the second [2] option more?
> I prefer option [2]. The clock_prepare|unprepare() thingy in option
> [1], looks more like an odd workaround to me.
>
> Does that make sense to you as well?

I don't have a strong preference since both variants give the same
effect. I'll keep testing option [2] and will use it in the next version
if no problem will be found. Thank you!