summaryrefslogtreecommitdiff
path: root/drivers/thermal/fair_share.c
AgeCommit message (Collapse)Author
2016-08-08thermal: fix race condition when updating cooling deviceMichele Di Giorgio
When multiple thermal zones are bound to the same cooling device, multiple kernel threads may want to update the cooling device state by calling thermal_cdev_update(). Having cdev not protected by a mutex can lead to a race condition. Consider the following situation with two kernel threads k1 and k2: Thread k1 Thread k2 || || call thermal_cdev_update() || ... || set_cur_state(cdev, target); call power_actor_set_power() || ... || instance->target = state; || cdev->updated = false; || || cdev->updated = true; || // completes execution call thermal_cdev_update() || // cdev->updated == true || return; || \/ time k2 has already looped through the thermal instances looking for the deepest cooling device state and is preempted right before setting cdev->updated to true. Now, k1 runs, modifies the thermal instance state and sets cdev->updated to false. Then, k1 is preempted and k2 continues the execution by setting cdev->updated to true, therefore preventing k1 from performing the update. Notice that this is not an issue if k2 looks at the instance->target modified by k1 "after" it is assigned by k1. In fact, in this case the update will happen anyway and k1 can safely return immediately from thermal_cdev_update(). This may lead to a situation where a thermal governor never updates the cooling device. For example, this is the case for the step_wise governor: when calling the function thermal_zone_trip_update(), the governor may always get a new state equal to the old one (which, however, wasn't notified to the cooling device) and will therefore skip the update. CC: Zhang Rui <rui.zhang@intel.com> CC: Eduardo Valentin <edubezval@gmail.com> CC: Peter Feuerer <peter@piie.net> Reported-by: Toby Huang <toby.huang@arm.com> Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com> Reviewed-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
2015-08-03thermal: consistently use int for temperaturesSascha Hauer
The thermal code uses int, long and unsigned long for temperatures in different places. Using an unsigned type limits the thermal framework to positive temperatures without need. Also several drivers currently will report temperatures near UINT_MAX for temperatures below 0°C. This will probably immediately shut the machine down due to overtemperature if started below 0°C. 'long' is 64bit on several architectures. This is not needed since INT_MAX °mC is above the melting point of all known materials. Consistently use a plain 'int' for temperatures throughout the thermal code and the drivers. This only changes the places in the drivers where the temperature is passed around as pointer, when drivers internally use another type this is not changed. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Jean Delvare <jdelvare@suse.de> Reviewed-by: Lukasz Majewski <l.majewski@samsung.com> Reviewed-by: Darren Hart <dvhart@linux.intel.com> Reviewed-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Peter Feuerer <peter@piie.net> Cc: Punit Agrawal <punit.agrawal@arm.com> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Jean Delvare <jdelvare@suse.de> Cc: Peter Feuerer <peter@piie.net> Cc: Heiko Stuebner <heiko@sntech.de> Cc: Lukasz Majewski <l.majewski@samsung.com> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: linux-acpi@vger.kernel.org Cc: platform-driver-x86@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-omap@vger.kernel.org Cc: linux-samsung-soc@vger.kernel.org Cc: Guenter Roeck <linux@roeck-us.net> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Maxime Ripard <maxime.ripard@free-electrons.com> Cc: Darren Hart <dvhart@infradead.org> Cc: lm-sensors@lm-sensors.org Signed-off-by: Zhang Rui <rui.zhang@intel.com>
2015-05-04thermal: fair_share: generalize the weight conceptJavi Merino
The fair share governor has the concept of weights, which is the influence of each cooling device in a thermal zone. The current implementation forces the weights of all cooling devices in a thermal zone to add up to a 100. This complicates setups, as you need to know in advance how many cooling devices you are going to have. If you bind a new cooling device, you have to modify all the other cooling devices weights, which is error prone. Furthermore, you can't specify a "default" weight for platforms since that default value depends on the number of cooling devices in the platform. This patch generalizes the concept of weight by allowing any number to be a "weight". Weights are now relative to each other. Platforms that don't specify weights get the same default value for all their cooling devices, so all their cdevs are considered to be equally influential. It's important to note that previous users of the weights don't need to alter the code: percentages continue to work as they used to. This patch just removes the constraint of all the weights in a thermal zone having to add up to a 100. If they do, you get the same behavior as before. If they don't, fair share now works for that platform. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Durgadoss R <durgadoss.r@intel.com> Acked-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
2015-05-04thermal: fair_share: fix typoJavi Merino
s/asscciated/associated/ Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Durgadoss R <durgadoss.r@intel.com> Reviewed-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
2015-05-04thermal: fair_share: use the weight from the thermal instanceJavi Merino
The fair share governor is not usable with thermal zones that use the bind op and don't populate thermal_zone_parameters, the majority of them. Now that the weight is in the thermal instance, we can use that in the fair share governor to allow every thermal zone to trivially use this governor. Furthermore, this simplifies the code. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Durgadoss R <durgadoss.r@intel.com> Reviewed-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
2015-05-04thermal: of: fix cooling device weights in device treeKapileshwar Singh
Currently you can specify the weight of the cooling device in the device tree but that information is not populated to the thermal_bind_params where the fair share governor expects it to be. The of thermal zone device doesn't have a thermal_bind_params structure and arguably it's better to pass the weight inside the thermal_instance as it is specific to the bind of a cooling device to a thermal zone parameter. Core thermal code is fixed to populate the weight in the instance from the thermal_bind_params, so platform code that was passing the weight inside the thermal_bind_params continue to work seamlessly. While we are at it, create a default value for the weight parameter for those thermal zones that currently don't define it and remove the hardcoded default in of-thermal. Cc: Zhang Rui <rui.zhang@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Peter Feuerer <peter@piie.net> Cc: Darren Hart <dvhart@infradead.org> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Kukjin Kim <kgene@kernel.org> Cc: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Kapileshwar Singh <kapileshwar.singh@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
2014-07-29thermal: trace: Trace when temperature is above a trip pointPunit Agrawal
Create a new event to trace when the temperature is above a trip point. Use the trace-point when handling non-critical and critical trip pionts. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
2013-04-14Thermal: build thermal governors into thermal_sys moduleZhang Rui
The thermal governors are part of the thermal framework, rather than a seperate feature/module. Because the generic thermal layer can not work without thermal governors, and it must load the thermal governors during its initialization. Build them into one module in this patch. This also fix a problem that the generic thermal layer does not work when CONFIG_THERMAL=m and CONFIG_THERMAL_GOV_XXX=y. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Eduardo Valentin <eduardo.valentin@ti.com> Acked-by: Durgadoss R <durgadoss.r@intel.com>
2012-11-05thermal: fair_share: Add missing static storage class specifiersSachin Kamat
Fixes the following sparse warnings: drivers/thermal/fair_share.c:80:5: warning: symbol 'fair_share_throttle' was not declared. Should it be static? drivers/thermal/fair_share.c:111:25: warning: symbol 'thermal_gov_fair_share' was not declared. Should it be static? Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Acked-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
2012-11-05Thermal: Introduce fair_share thermal governorDurgadoss R
This patch introduces a simple 'weight' based governor named fair_share governor. Whenever the thermal framework gets notified of the trip point violation, this governor (if configured), throttles the cooling devices associated with a thermal zone. This mapping between a thermal zone and a cooling device and the effectiveness of cooling are provided in the platform layer. Signed-off-by: Durgadoss R <durgadoss.r@intel.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>