linux-kernel - Re: [PATCH v1 09/16] thermal: gov_step_wise: Use trip thresholds instead of trip temperatures

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Date: Fri, 19 Apr 2024 20:11:51 +0100
From: Lukasz Luba <lukasz.luba@....com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: LKML <linux-kernel@...r.kernel.org>, Linux PM <linux-pm@...r.kernel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v1 09/16] thermal: gov_step_wise: Use trip thresholds
 instead of trip temperatures



On 4/10/24 17:43, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> In principle, the Step-Wise governor should take trip hystereses into

s/hystereses/hysteresis/

> account.  After all, once a trip has been crossed on the way up,
> mitigation is still needed until it is crossed on the way down.
> 
> For this reason, make it use trip thresholds that are computed by
> the core when trips are crossed, so as to apply mitigations in the
> hysteresis rages of trips that were crossed on the way up, but have
> not been crossed on the way down yet.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>   drivers/thermal/gov_step_wise.c |    9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> Index: linux-pm/drivers/thermal/gov_step_wise.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_step_wise.c
> +++ linux-pm/drivers/thermal/gov_step_wise.c
> @@ -62,7 +62,8 @@ static unsigned long get_target_state(st
>   }
>   
>   static void thermal_zone_trip_update(struct thermal_zone_device *tz,
> -				     const struct thermal_trip *trip)
> +				     const struct thermal_trip *trip,
> +				     int trip_threshold)
>   {
>   	int trip_id = thermal_zone_trip_id(tz, trip);
>   	enum thermal_trend trend;
> @@ -72,13 +73,13 @@ static void thermal_zone_trip_update(str
>   
>   	trend = get_tz_trend(tz, trip);
>   
> -	if (tz->temperature >= trip->temperature) {
> +	if (tz->temperature >= trip_threshold) {

So this value in 'trip_threshold' might be lower than older
'trip->temperature', but not necessarily. Anyway, all good here.

>   		throttle = true;
>   		trace_thermal_zone_trip(tz, trip_id, trip->type);
>   	}
>   
>   	dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
> -		trip_id, trip->type, trip->temperature, trend, throttle);
> +		trip_id, trip->type, trip_threshold, trend, throttle);
>   
>   	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>   		if (instance->trip != trip)
> @@ -131,7 +132,7 @@ static void step_wise_manage(struct ther
>   		    trip->type == THERMAL_TRIP_HOT)
>   			continue;
>   
> -		thermal_zone_trip_update(tz, trip);
> +		thermal_zone_trip_update(tz, trip, td->threshold);
>   	}
>   
>   	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> 
> 
> 


LGTM w/ spelling fixed.

Reviewed-by: Lukasz Luba <lukasz.luba@....com>