On Wed, 16 Sep 2020 at 23:22, Thara Gopinath <thara.gopinath@xxxxxxxxxx> wrote: > > Thermal framework today supports monitoring for rising temperatures and > subsequently initiating cooling action in case of a thermal trip point > being crossed. There are scenarios where a SoC need warming mitigating > action to be activated if the temperature falls below a cetain permissible > limit. Since warming action can be considered mirror opposite of cooling > action, most of the thermal framework can be re-used to achieve this. The > key assumption in this patch series is that a device can act either as a > warming device or a cooling device and not as both. > > In order to support warming three extensions are needed in the thermal > framework. > > 1. Indication that a trip point is being monitored for falling temperature > and not rising temperature. We discussed two different ways to achieve this > during LPC. First option is to introduce a new trip type to indicate that a > trip is a cold trip(THERMAL_TRIP_COLD). The second option is to introduce a > new property for trip point that will indicate whether a trip point is > being monitored for rising temperature or falling temperature. The patch > series(patches 1-4) chooses the second approach since it allows trip points > of any type to be monitored for rising or falling temperature.Also this was > the preferred approach when discussed during LPC. The approach that > introduces a new cold trip type was posted on the list earlier as a RFC and > can be found at [1]. > > 2. Extend the exisitng governors to handle monitoring of falling > temperature. The patch series(patches 5 & 6) extends the step wise governor > to monitor the falling temperature.Other governors return doing nothing if > the trip point they are being called for is being monitored for falling > temperature. The governors' mitigate function is called "throttle" in the > thermal framework and with this patch series it is a misnomer as the > function is called for both throttling and warming up. Ideally > "throttle" should be renamed to "mitigate" to improve readability of code. > The renaming is not part of this series. > > 3. Finally, the cooling device framework itself can be reused for a warming > device. As stated before a device can act either as a warming device or a > cooling device and not as both. With this the cooling state in the > framework can be considered as mitigating state with 0 as the state with no > thermal mitigation and higher the number higher the thermal mitigation. > Again what affects the code readability and comprehension is the term > "cooling" which is a misnomer here. Ideally the term "cooling" should be > renamed to "mitigating" and hence thermal_cooling_device will become > thermal_mitgating_device. The renaming is not part of the patch series as > even though the renaming is a simple search-replace, it will change a lot > of files. The patch series(patches 7 & 8) instead introduces a minimal set > of _warming_device_ apis to register and unregister warming devices which > internally is identical to the _cooling_device_ counterpart. Gentle ping for review.. > > 1. https://lkml.org/lkml/2020/7/10/639 > > Thara Gopinath (8): > dt-bindings: thermal: Introduce monitor-falling parameter to thermal > trip point binding > thermal: Introduce new property monitor_type for trip point. > thermal: thermal_of: Extend thermal dt driver to support > bi-directional monitoring of a thermal trip point. > thermal:core:Add genetlink notifications for monitoring falling > temperature > thermal: gov_step_wise: Extend thermal step-wise governor to monitor > falling temperature. > thermal: Modify thermal governors to do nothing for trip points being > monitored for falling temperature > thermal:core: Add is_warming_dev and supporting warming device api's > to the cooling dev framework. > soc:qcom:qcom_aoss: Change cooling_device_register to > warming_device_register > > .../bindings/thermal/thermal-zones.yaml | 7 ++ > drivers/soc/qcom/qcom_aoss.c | 6 +- > drivers/thermal/gov_bang_bang.c | 12 ++ > drivers/thermal/gov_fair_share.c | 12 ++ > drivers/thermal/gov_power_allocator.c | 12 ++ > drivers/thermal/gov_step_wise.c | 62 +++++++--- > drivers/thermal/thermal_core.c | 113 +++++++++++++++--- > drivers/thermal/thermal_core.h | 2 + > drivers/thermal/thermal_of.c | 22 ++++ > include/linux/thermal.h | 9 ++ > include/uapi/linux/thermal.h | 5 + > 11 files changed, 226 insertions(+), 36 deletions(-) > > -- > 2.25.1 > -- Warm Regards Thara
