thermal: gov_step_wise: Use trip thresholds instead of trip temperatures

In principle, the Step-Wise governor should take trip hysteresis into
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@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/gov_step_wise.c

@@ -62,7 +62,8 @@ static unsigned long get_target_state(struct thermal_instance *instance,
 }
 
 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(struct thermal_zone_device *tz,
 
 	trend = get_tz_trend(tz, trip);
 
-	if (tz->temperature >= trip->temperature) {
+	if (tz->temperature >= trip_threshold) {
 		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 thermal_zone_device *tz)
 		    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)