linux-kernel - Re: [PATCH] OPP: Fix support for required OPPs for multiple PM domains

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Message-ID: <CAPDyKFoA9O5a6xZ+948QOzYqsRjk_0jJaSxeYRwx=76YsLHzXQ@mail.gmail.com>
Date: Wed, 10 Jul 2024 15:51:35 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>, 
	Nikunj Kela <nkela@...cinc.com>, Prasad Sodagudi <psodagud@...cinc.com>, linux-pm@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-tegra@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] OPP: Fix support for required OPPs for multiple PM domains

On Tue, 2 Jul 2024 at 07:15, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 01-07-24, 17:17, Viresh Kumar wrote:
> > What about this patch instead ?
> >
> > diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> > index 5f4598246a87..2086292f8355 100644
> > --- a/drivers/opp/core.c
> > +++ b/drivers/opp/core.c
> > @@ -1091,7 +1091,8 @@ static int _set_required_opps(struct device *dev, struct opp_table *opp_table,
> >               if (devs[index]) {
> >                       required_opp = opp ? opp->required_opps[index] : NULL;
> >
> > -                     ret = dev_pm_opp_set_opp(devs[index], required_opp);
> > +                     /* Set required OPPs forcefully */
> > +                     ret = dev_pm_opp_set_opp_forced(devs[index], required_opp, true);
>
> Maybe better to do just this instead:
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 5f4598246a87..9484acbeaa66 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1386,7 +1386,12 @@ int dev_pm_opp_set_opp(struct device *dev, struct dev_pm_opp *opp)
>                 return PTR_ERR(opp_table);
>         }
>
> -       ret = _set_opp(dev, opp_table, opp, NULL, false);
> +       /*
> +        * For a genpd's OPP table, we always want to set the OPP (and
> +        * performance level) and let the genpd core take care of aggregating
> +        * the votes. Set `forced` to true for a genpd here.
> +        */
> +       ret = _set_opp(dev, opp_table, opp, NULL, opp_table->is_genpd);
>         dev_pm_opp_put_opp_table(opp_table);

I think this should work, but in this case we seem to need a similar
thing for dev_pm_opp_set_rate().

Another option is to let _set_opp() check "opp_table->is_genpd" and
enforce the opp to be set in that case. Whatever you prefer, I can
re-spin the patch.

Kind regards
Uffe