From 9685ce100f0d302501117113ef0a526ad1acca1d Mon Sep 17 00:00:00 2001 From: Ram Chandrasekar Date: Mon, 7 May 2018 11:54:08 -0600 Subject: [PATCH] drivers: thermal: step_wise: add support for hysteresis Step wise governor increases the mitigation level when the temperature goes above a threshold and will decrease the mitigation when the temperature falls below the threshold. If it were a case, where the temperature hovers around a threshold, the mitigation will be applied and removed at every iteration. This reaction to the temperature is inefficient for performance. The use of hysteresis temperature could avoid this ping-pong of mitigation by relaxing the mitigation to happen only when the temperature goes below this lower hysteresis value. Signed-off-by: Ram Chandrasekar Signed-off-by: Lina Iyer [forward-ported for Linux 6.6, as stop-gap downstream solution] Signed-off-by: Daniel Golle --- drivers/thermal/gov_step_wise.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) --- a/drivers/thermal/gov_step_wise.c +++ b/drivers/thermal/gov_step_wise.c @@ -86,22 +86,31 @@ static void thermal_zone_trip_update(str struct thermal_instance *instance; bool throttle = false; int old_target; + int hyst_temp; trend = get_tz_trend(tz, trip_id); - if (tz->temperature >= trip->temperature) { - 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); + hyst_temp = trip->temperature - trip->hysteresis; + dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d,hyst=%d]:trend=%d,throttle=%d\n", + trip_id, trip->type, trip->temperature, hyst_temp, trend, throttle); list_for_each_entry(instance, &tz->thermal_instances, tz_node) { if (instance->trip != trip) continue; old_target = instance->target; + throttle = false; + /* + * Lower the mitigation only if the temperature + * goes below the hysteresis temperature. + */ + if (tz->temperature >= trip->temperature || + (tz->temperature >= hyst_temp && + old_target != THERMAL_NO_TARGET)) { + throttle = true; + trace_thermal_zone_trip(tz, trip_id, trip->type); + } + instance->target = get_target_state(instance, trend, throttle); dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", old_target, (int)instance->target);