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![Eduardo Valentin](/assets/img/avatar_default.png)
In case the trend is not changing or when there is no request for throttling, it is expected that the instance would not change its requested target. This patch improves the code implementation to cover for this expected behavior. With current implementation, the instance will always reset to cdev.cur_state, even in not expected cases, like those mentioned above. This patch changes the step_wise governor implementation of get_target so that we accomplish: (a) - default value will be current instance->target, so we do not change the thermal instance target unnecessarily. (b) - the code now it is clear about what is the intention. There is a clear statement of what are the expected outcomes (c) - removal of hardcoded constants, now it is put in use the THERMAL_NO_TARGET macro. (d) - variable names are also improved so that reader can clearly understand the difference between instance cur target, next target and cdev cur_state. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Durgadoss R <durgadoss.r@intel.com> Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reported-by: Ruslan Ruslichenko <ruslan.ruslichenko@ti.com> Signed-of-by: Eduardo Valentin <eduardo.valentin@ti.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
206 lines
6 KiB
C
206 lines
6 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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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 "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, use lower cooling
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* state for this trip point
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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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* deactive 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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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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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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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 || type == THERMAL_TRIPS_NONE)
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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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long 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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if (trip == THERMAL_TRIPS_NONE) {
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trip_temp = tz->forced_passive;
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trip_type = THERMAL_TRIPS_NONE;
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} else {
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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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}
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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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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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if (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->cdev->updated = false; /* cdev needs update */
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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 asscciated with the given zone
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* @tz - thermal_zone_device
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* @trip - the trip point
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* @trip_type - type of the trip point
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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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if (tz->forced_passive)
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thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
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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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int thermal_gov_step_wise_register(void)
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{
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return thermal_register_governor(&thermal_gov_step_wise);
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}
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void thermal_gov_step_wise_unregister(void)
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{
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thermal_unregister_governor(&thermal_gov_step_wise);
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}
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