From cef4ba037209392aa6437357c27ba7c450936e36 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 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 drivers: thermal: step_wise: avoid throttling at hysteresis temperature after dropping below it Signed-off-by: Serge Schneider Fix hysteresis support in gov_step_wise.c Directly get hyst value instead of going through an optional and, now, unimplemented function. Signed-off-by: Jürgen Kreileder --- drivers/thermal/gov_step_wise.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) --- a/drivers/thermal/gov_step_wise.c +++ b/drivers/thermal/gov_step_wise.c @@ -17,11 +17,11 @@ #include "thermal_core.h" /* - * If the temperature is higher than a trip point, + * If the temperature is higher than a hysteresis temperature, * a. if the trend is THERMAL_TREND_RAISING, use higher cooling * state for this trip point * b. if the trend is THERMAL_TREND_DROPPING, do nothing - * If the temperature is lower than a trip point, + * If the temperature is lower than a hysteresis temperature, * a. if the trend is THERMAL_TREND_RAISING, do nothing * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling * state for this trip point, if the cooling state already @@ -74,19 +74,35 @@ static void thermal_zone_trip_update(str int trip_id = thermal_zone_trip_id(tz, trip); struct thermal_instance *instance; bool throttle = false; + int hyst_temp; 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_threshold, 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, &td->thermal_instances, trip_node) { int old_target; 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 == instance->upper)) { + 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=%ld\n",