linux-kernel - Re: [PATCH V4 2/4] cpufreq: intel_pstate: Migrate to ->offline() instead of ->stop

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Date:   Wed, 30 Jun 2021 18:58:39 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 2/4] cpufreq: intel_pstate: Migrate to ->offline()
 instead of ->stop_cpu()

On Thu, Jun 24, 2021 at 3:52 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 23-06-21, 17:13, Rafael J. Wysocki wrote:
> > As mentioned already in
> >
> > https://lore.kernel.org/linux-pm/CAJZ5v0g2tCZptcqh+c55YYiO7rDHmZivMLsmpq_7005zNPN1xg@mail.gmail.com/
>
> Sorry about failing to reply over that, I got confused somehow..
>
> > this isn't particularly clean, because intel_pstate_cpu_offline() is
> > also used in the passive mode where the above call is not needed.
>
> intel_pstate_clear_update_util_hook() returns early if the hook was never
> registered, and so calling it was safe, but yes not very clean.
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Subject: [PATCH] cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline()
> >
> > Combine the ->stop_cpu() and ->offline() callback routines for the
> > active mode of intel_pstate so as to avoid setting the ->stop_cpu
> > callback pointer which is going to be dropped from the framework.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >  drivers/cpufreq/intel_pstate.c |    7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > Index: linux-pm/drivers/cpufreq/intel_pstate.c
> > ===================================================================
> > --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> > +++ linux-pm/drivers/cpufreq/intel_pstate.c
> > @@ -2577,11 +2577,13 @@ static int intel_pstate_cpu_online(struc
> >       return 0;
> >  }
> >
> > -static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
> > +static int intel_pstate_stop_cpu(struct cpufreq_policy *policy)
> >  {
> >       pr_debug("CPU %d stopping\n", policy->cpu);
> >
> >       intel_pstate_clear_update_util_hook(policy->cpu);
> > +
> > +     return intel_pstate_cpu_offline(policy);
> >  }
> >
> >  static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
> > @@ -2654,8 +2656,7 @@ static struct cpufreq_driver intel_pstat
> >       .resume         = intel_pstate_resume,
> >       .init           = intel_pstate_cpu_init,
> >       .exit           = intel_pstate_cpu_exit,
> > -     .stop_cpu       = intel_pstate_stop_cpu,
> > -     .offline        = intel_pstate_cpu_offline,
> > +     .offline        = intel_pstate_stop_cpu,
>
> I would suggest to rename intel_pstate_cpu_offline() as
> intel_cpufreq_cpu_offline() and intel_pstate_stop_cpu() as
> intel_pstate_cpu_offline(), so we remove the stop-cpu terminology completely.

I have followed the above suggestion and applied the modified patch
along with the rest of this series.

> Either way:
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

Thanks!

> >       .online         = intel_pstate_cpu_online,
> >       .update_limits  = intel_pstate_update_limits,
> >       .name           = "intel_pstate",