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drivers: thermal: step_wise: add support for hysteresis

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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 <rkumbako@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>

drivers: thermal: step_wise: avoid throttling at hysteresis temperature after dropping below it

Signed-off-by: Serge Schneider <serge@raspberrypi.org>

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 <jk@blackdown.de>
This commit is contained in:
Ram Chandrasekar
2018-05-07 11:54:08 -06:00
committed by Dom Cobley
parent df4c206863
commit f236761a15
1 changed files with 20 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/thermal/gov_step_wise.c
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@@ -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
@@ -73,14 +73,18 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz,
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, &tz->thermal_instances, tz_node) {
int old_target;
@@ -89,6 +93,18 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz,
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 == 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",