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![Daniel Lezcano](/assets/img/avatar_default.png)
The code was reorganized in 2012 with the commit 0c01ebbfd3
.
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
201 lines
5.7 KiB
C
201 lines
5.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* step_wise.c - A step-by-step Thermal throttling governor
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*
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* Copyright (C) 2012 Intel Corp
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* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#include <linux/thermal.h>
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#include <trace/events/thermal.h>
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#include "thermal_core.h"
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/*
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* If the temperature is higher than a trip point,
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* a. if the trend is THERMAL_TREND_RAISING, use higher cooling
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* state for this trip point
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* b. if the trend is THERMAL_TREND_DROPPING, do nothing
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* c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit
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* for this trip point
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* d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
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* for this trip point
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* If the temperature is lower than a trip point,
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* a. if the trend is THERMAL_TREND_RAISING, do nothing
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* b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
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* state for this trip point, if the cooling state already
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* equals lower limit, deactivate the thermal instance
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* c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing
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* d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit,
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* if the cooling state already equals lower limit,
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* deactivate the thermal instance
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*/
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static unsigned long get_target_state(struct thermal_instance *instance,
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enum thermal_trend trend, bool throttle)
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{
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struct thermal_cooling_device *cdev = instance->cdev;
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unsigned long cur_state;
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unsigned long next_target;
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/*
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* We keep this instance the way it is by default.
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* Otherwise, we use the current state of the
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* cdev in use to determine the next_target.
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*/
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cdev->ops->get_cur_state(cdev, &cur_state);
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next_target = instance->target;
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dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
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if (!instance->initialized) {
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if (throttle) {
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next_target = (cur_state + 1) >= instance->upper ?
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instance->upper :
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((cur_state + 1) < instance->lower ?
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instance->lower : (cur_state + 1));
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} else {
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next_target = THERMAL_NO_TARGET;
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}
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return next_target;
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}
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switch (trend) {
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case THERMAL_TREND_RAISING:
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if (throttle) {
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next_target = cur_state < instance->upper ?
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(cur_state + 1) : instance->upper;
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if (next_target < instance->lower)
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next_target = instance->lower;
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}
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break;
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case THERMAL_TREND_RAISE_FULL:
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if (throttle)
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next_target = instance->upper;
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break;
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case THERMAL_TREND_DROPPING:
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if (cur_state <= instance->lower) {
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if (!throttle)
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next_target = THERMAL_NO_TARGET;
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} else {
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if (!throttle) {
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next_target = cur_state - 1;
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if (next_target > instance->upper)
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next_target = instance->upper;
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}
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}
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break;
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case THERMAL_TREND_DROP_FULL:
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if (cur_state == instance->lower) {
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if (!throttle)
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next_target = THERMAL_NO_TARGET;
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} else
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next_target = instance->lower;
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break;
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default:
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break;
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}
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return next_target;
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}
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static void update_passive_instance(struct thermal_zone_device *tz,
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enum thermal_trip_type type, int value)
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{
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/*
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* If value is +1, activate a passive instance.
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* If value is -1, deactivate a passive instance.
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*/
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if (type == THERMAL_TRIP_PASSIVE)
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tz->passive += value;
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}
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static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
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{
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int trip_temp;
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enum thermal_trip_type trip_type;
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enum thermal_trend trend;
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struct thermal_instance *instance;
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bool throttle = false;
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int old_target;
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tz->ops->get_trip_temp(tz, trip, &trip_temp);
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tz->ops->get_trip_type(tz, trip, &trip_type);
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trend = get_tz_trend(tz, trip);
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if (tz->temperature >= trip_temp) {
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throttle = true;
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trace_thermal_zone_trip(tz, trip, trip_type);
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}
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dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
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trip, trip_type, trip_temp, trend, throttle);
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mutex_lock(&tz->lock);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
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if (instance->trip != trip)
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continue;
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old_target = instance->target;
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instance->target = get_target_state(instance, trend, throttle);
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dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
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old_target, (int)instance->target);
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if (instance->initialized && old_target == instance->target)
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continue;
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/* Activate a passive thermal instance */
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if (old_target == THERMAL_NO_TARGET &&
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instance->target != THERMAL_NO_TARGET)
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update_passive_instance(tz, trip_type, 1);
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/* Deactivate a passive thermal instance */
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else if (old_target != THERMAL_NO_TARGET &&
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instance->target == THERMAL_NO_TARGET)
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update_passive_instance(tz, trip_type, -1);
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instance->initialized = true;
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mutex_lock(&instance->cdev->lock);
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instance->cdev->updated = false; /* cdev needs update */
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mutex_unlock(&instance->cdev->lock);
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}
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mutex_unlock(&tz->lock);
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}
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/**
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* step_wise_throttle - throttles devices associated with the given zone
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* @tz: thermal_zone_device
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* @trip: trip point index
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*
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* Throttling Logic: This uses the trend of the thermal zone to throttle.
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* If the thermal zone is 'heating up' this throttles all the cooling
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* devices associated with the zone and its particular trip point, by one
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* step. If the zone is 'cooling down' it brings back the performance of
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* the devices by one step.
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*/
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static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
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{
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struct thermal_instance *instance;
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thermal_zone_trip_update(tz, trip);
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mutex_lock(&tz->lock);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node)
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thermal_cdev_update(instance->cdev);
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mutex_unlock(&tz->lock);
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return 0;
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}
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static struct thermal_governor thermal_gov_step_wise = {
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.name = "step_wise",
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.throttle = step_wise_throttle,
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};
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THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
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