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

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Date:   Thu, 24 Jun 2021 07:22:28 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V4 2/4] cpufreq: intel_pstate: Migrate to ->offline()
 instead of ->stop_cpu()

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.

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

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

-- 
viresh