Re: [PATCH v2 28/48] soc/tegra: Introduce core power domain driver

[Viresh Kumar]

On 22-12-20, 22:39, Dmitry Osipenko wrote:
> 22.12.2020 22:21, Dmitry Osipenko пишет:
> >>> +	if (IS_ERR(opp)) {
> >>> +		dev_err(&genpd->dev, "failed to find OPP for level %u: %pe\n",
> >>> +			level, opp);
> >>> +		return PTR_ERR(opp);
> >>> +	}
> >>> +
> >>> +	err = dev_pm_opp_set_voltage(&genpd->dev, opp);
> >> IIUC, you implemented this callback because you want to use the voltage triplet
> >> present in the OPP table ?
> >>
> >> And so you are setting the regulator ("power") later in this patch ?
> > yes
> > 
> >> I am not in favor of implementing this routine, as it just adds a wrapper above
> >> the regulator API. What you should be doing rather is get the regulator by
> >> yourself here (instead of depending on the OPP core). And then you can do
> >> dev_pm_opp_get_voltage() here and set the voltage yourself. You may want to
> >> implement a version supporting triplet here though for the same.
> >>
> >> And you won't require the sync version of the API as well then.
> >>
> > That's what I initially did for this driver. I don't mind to revert back
> > to the initial variant in v3, it appeared to me that it will be nicer
> > and cleaner to have OPP API managing everything here.
> 
> I forgot one important detail (why the initial variant wasn't good)..
> OPP entries that have unsupportable voltages should be filtered out and
> OPP core performs the filtering only if regulator is assigned to the OPP
> table.
> 
> If regulator is assigned to the OPP table, then we need to use OPP API
> for driving the regulator, hence that's why I added
> dev_pm_opp_sync_regulators() and dev_pm_opp_set_voltage().
> 
> Perhaps it should be possible to add dev_pm_opp_get_regulator() that

What's wrong with getting the regulator in the driver as well ? Apart from the
OPP core ?

> will return the OPP table regulator in order to allow driver to use the
> regulator directly. But I'm not sure whether this is a much better
> option than the opp_sync_regulators() and opp_set_voltage() APIs.

set_voltage() is still fine as there is some data that the OPP core has, but
sync_regulator() has nothing to do with OPP core.

And this may lead to more wrapper helpers in the OPP core, which I am afraid of.
And so even if it is not the best, I would like the OPP core to provide the data
and not get into this. Ofcourse there is an exception to this, opp_set_rate.

-- 
viresh