Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper

[Dmitry Osipenko]

18.08.2021 12:41, Ulf Hansson пишет:
> On Wed, 18 Aug 2021 at 11:14, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>>
>> On 18-08-21, 10:29, Ulf Hansson wrote:
>>> Me and Dmitry discussed adding a new genpd callback for this. I agreed
>>> that it seems like a reasonable thing to add, if he insists.

Either way gives the equal result. The new callback allows to remove the
boilerplate dev_pm_opp_set_rate(clk_get_rate() code from the rpm-resume
of consumer devices, that's it.

>>> The intent was to invoke the new callback from __genpd_dev_pm_attach()
>>> when the device has been attached to its genpd. This allows the
>>> callback, to invoke clk_get_rate() and then dev_pm_opp_set_rate(), to
>>> update the vote according to the current state of the HW.
>>
>> I wouldn't call dev_pm_opp_set_rate() from there, since it means
>> configure and enable (both) for different resources, clk, regulator,
>> genpd, etc..
> 
> Right, good point!
> 
> dev_pm_opp_set_rate() is best called from consumer drivers, as they
> need to be in control.
>> What we need here is just configure. So something like this then:
The intent wasn't to use dev_pm_opp_set_rate() from
__genpd_dev_pm_attach(), but to set genpd->rpm_pstate in accordance to
the h/w configuration.

On Tegra we have a chain of PDs and it's not trivial to convert the
device's OPP into pstate because only the parent domain can translate
the required OPP.

Viresh, please take a look at what I did in [1]. Maybe it could be done
in another way.

[1]
https://patchwork.ozlabs.org/project/linux-tegra/patch/20210701232728.23591-3-digetx@xxxxxxxxx/