thermal/core: Remove the 'forced_passive' option

The code was reorganized in 2012 with the commit 0c01ebbfd3caf1.

The main change is a loop on the trip points array and a unconditional
call to the throttle() ops of the governors for each of them even if
the trip temperature is not reached yet.

With this change, the 'forced_passive' is no longer checked in the
thermal_zone_device_update() function but in the step wise governor's
throttle() callback.

As the force_passive does no belong to the trip point array, the
thermal_zone_device_update() can not compare with the specified
passive temperature, thus does not detect the passive limit has been
crossed. Consequently, throttle() is never called and the
'forced_passive' branch is unreached.

In addition, the default processor cooling device is not automatically
bound to the thermal zone if there is not passive trip point, thus the
'forced_passive' can not operate.

If there is an active trip point, then the throttle function will be
called to mitigate at this temperature and the 'forced_passive' will
override the mitigation of the active trip point in this case but with
the default cooling device bound to the thermal zone, so usually a
fan, and that is not a passive cooling effect.

Given the regression exists since more than 8 years, nobody complained
and at the best of my knowledge there is no bug open in
https://bugzilla.kernel.org, it is reasonable to say it is unused.

Remove the 'forced_passive' related code.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Link: https://lore.kernel.org/r/20201214233811.485669-1-daniel.lezcano@linaro.org

1 files changed, 3 insertions, 11 deletions

diff --git a/drivers/thermal/gov_step_wise.c b/drivers/thermal/gov_step_wise.c
index 2ae7198d3067..12acb12aac50 100644
--- a/drivers/thermal/gov_step_wise.c
+++ b/drivers/thermal/gov_step_wise.c
@@ -109,7 +109,7 @@ static void update_passive_instance(struct thermal_zone_device *tz,
 	 * If value is +1, activate a passive instance.
 	 * If value is -1, deactivate a passive instance.
 	 */
-	if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
+	if (type == THERMAL_TRIP_PASSIVE)
 		tz->passive += value;
 }
 
@@ -122,13 +122,8 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 	bool throttle = false;
 	int old_target;
 
-	if (trip == THERMAL_TRIPS_NONE) {
-		trip_temp = tz->forced_passive;
-		trip_type = THERMAL_TRIPS_NONE;
-	} else {
-		tz->ops->get_trip_temp(tz, trip, &trip_temp);
-		tz->ops->get_trip_type(tz, trip, &trip_type);
-	}
+	tz->ops->get_trip_temp(tz, trip, &trip_temp);
+	tz->ops->get_trip_type(tz, trip, &trip_type);
 
 	trend = get_tz_trend(tz, trip);
 
@@ -189,9 +184,6 @@ static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 
 	thermal_zone_trip_update(tz, trip);
 
-	if (tz->forced_passive)
-		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
-
 	mutex_lock(&tz->lock);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node)