Re: [PATCH 1/2] OPP: Use _set_opp_level() for single genpd case

Viresh Kumar
2023-10-25T10:48:21Z

On 25-10-23, 12:40, Ulf Hansson wrote:
> On Wed, 25 Oct 2023 at 08:55, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > On 19-10-23, 13:16, Ulf Hansson wrote:
> > > On Thu, 19 Oct 2023 at 12:22, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > > > + if (required_table->is_genpd && opp_table->required_opp_count == 1 &&
> > > > + !opp_table->genpd_virt_devs) {
> > > > + if (!WARN_ON(opp->level))
> > >
> > > Hmm. Doesn't this introduce an unnecessary limitation?
> > >
> > > An opp node that has a required-opps phande, may have "opp-hz",
> > > "opp-microvolt", etc. Why would we not allow the "opp-level" to be
> > > used too?
> >
> > Coming back to this, why would we ever want a device to have "opp-level" and
> > "required-opp" (set to genpd's table) ? That would mean we will call:
> >
> > dev_pm_domain_set_performance_state() twice to set different level values.
>
> Yes - and that would be weird, especially since the PM domain (genpd)
> is already managing the aggregation and propagation to parent domains.
>
> I guess I got a bit confused by the commit message for patch2/2, where
> it sounded like you were striving towards introducing recursive calls
> to set OPPs. Having a closer look, I realize that isn't the case,
> which I think makes sense.
>
> >
> > And so it should be safe to force that if required-opp table is set to a genpd,
> > then opp-level shouldn't be set. Maybe we should fail in that case, which isn't
> > happening currently.
>
> Yes, it seems better to fail earlier during the OF parsing of the
> required-opps or when adding an OPP dynamically. In that way, the
> WARN_ON above could be removed.

For now I will leave the WARN as is, will reconsider if it makes more
sense to fail and return early. And send a separate patch for that.

> That said, sorry for the noise and either way, feel free to add (for
> $subject patch):
>
> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Thanks.

--
viresh