897e721037
With interrupt driven thermal zones we pass the lower and upper temperature on which shall be acted, so in the governor we have to act on the exact lower temperature to be consistent. Otherwise an interrupt maybe generated on the exact lower temperature, but the bang bang governor does not react since The polling driven zones have to be one step cooler before the governor reacts. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Caesar Wang <wxt@rock-chips.com> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: linux-pm@vger.kernel.org Acked-by: Peter Feuerer <peter@piie.net> Signed-off-by: Eduardo Valentin <edubezval@gmail.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
139 lines
3.9 KiB
C
139 lines
3.9 KiB
C
/*
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* gov_bang_bang.c - A simple thermal throttling governor using hysteresis
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*
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* Copyright (C) 2014 Peter Feuerer <peter@piie.net>
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*
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* Based on step_wise.c with following Copyrights:
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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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* 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.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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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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static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
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{
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int trip_temp, trip_hyst;
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struct thermal_instance *instance;
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tz->ops->get_trip_temp(tz, trip, &trip_temp);
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if (!tz->ops->get_trip_hyst) {
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pr_warn_once("Undefined get_trip_hyst for thermal zone %s - "
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"running with default hysteresis zero\n", tz->type);
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trip_hyst = 0;
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} else
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tz->ops->get_trip_hyst(tz, trip, &trip_hyst);
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dev_dbg(&tz->device, "Trip%d[temp=%d]:temp=%d:hyst=%d\n",
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trip, trip_temp, tz->temperature,
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trip_hyst);
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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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/* in case fan is in initial state, switch the fan off */
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if (instance->target == THERMAL_NO_TARGET)
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instance->target = 0;
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/* in case fan is neither on nor off set the fan to active */
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if (instance->target != 0 && instance->target != 1) {
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pr_warn("Thermal instance %s controlled by bang-bang has unexpected state: %ld\n",
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instance->name, instance->target);
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instance->target = 1;
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}
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/*
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* enable fan when temperature exceeds trip_temp and disable
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* the fan in case it falls below trip_temp minus hysteresis
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*/
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if (instance->target == 0 && tz->temperature >= trip_temp)
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instance->target = 1;
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else if (instance->target == 1 &&
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tz->temperature <= trip_temp - trip_hyst)
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instance->target = 0;
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dev_dbg(&instance->cdev->device, "target=%d\n",
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(int)instance->target);
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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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* bang_bang_control - controls devices associated with the given zone
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* @tz - thermal_zone_device
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* @trip - the trip point
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*
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* Regulation Logic: a two point regulation, deliver cooling state depending
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* on the previous state shown in this diagram:
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*
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* Fan: OFF ON
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*
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* |
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* |
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* trip_temp: +---->+
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* | | ^
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* | | |
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* | | Temperature
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* (trip_temp - hyst): +<----+
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* |
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* |
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* |
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*
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* * If the fan is not running and temperature exceeds trip_temp, the fan
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* gets turned on.
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* * In case the fan is running, temperature must fall below
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* (trip_temp - hyst) so that the fan gets turned off again.
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*
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*/
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static int bang_bang_control(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_bang_bang = {
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.name = "bang_bang",
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.throttle = bang_bang_control,
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};
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int thermal_gov_bang_bang_register(void)
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{
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return thermal_register_governor(&thermal_gov_bang_bang);
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}
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void thermal_gov_bang_bang_unregister(void)
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{
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thermal_unregister_governor(&thermal_gov_bang_bang);
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}
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