[RFC PATCH 0/4] thermal: Introduce support for monitoring falling temperature

[Thara Gopinath <thara.gopinath@linaro.org>]

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 some warming 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.

This patch series is yet another attempt to add support for monitoring
falling temperature in thermal framework. Unlike the first attempt[1]
(where a new property was added to thermal trip point binding to indicate
direction of temperature monitoring), this series introduces a new trip
point type (THERMAL_TRIP_COLD) to indicate a trip point at which falling
temperature monitoring must be triggered. This patch series uses Daniel
Lezcano's recently added thermal genetlink interface[2] to notify userspace
of falling temperature and rising temperature at the cold trip point. This
will enable a user space engine to trigger the relevant mitigation for
falling temperature. At present, no support is added to any of the thermal
governors to monitor and mitigate falling temperature at the cold trip
point;rather all governors return doing nothing if triggered for a cold
trip point. As future extension, monitoring of falling temperature can be
added to the relevant thermal governor. 

Patch series introducing various resources that are used as warming devices
on Qualcomm sdm845:
https://lkml.org/lkml/2019/7/29/749 (already merged)
https://lkml.org/lkml/2020/6/3/1112 (under review)

1.https://lkml.org/lkml/2019/9/18/1180
2.https://lkml.org/lkml/2020/7/6/238 

Thara Gopinath (4):
  dt-bindings:thermal:Add cold trip point type
  thermal: Add support for cold trip point
  thermal:core:Add genetlink notifications for monitoring falling
    temperature
  thermal: Modify thermal governors to do nothing for "cold" trip points

 .../devicetree/bindings/thermal/thermal.txt   |  1 +
 drivers/thermal/gov_bang_bang.c               |  8 +++++++
 drivers/thermal/gov_fair_share.c              |  8 +++++++
 drivers/thermal/gov_power_allocator.c         |  8 +++++++
 drivers/thermal/gov_step_wise.c               |  8 +++++++
 drivers/thermal/thermal_core.c                | 21 +++++++++++++------
 drivers/thermal/thermal_of.c                  |  1 +
 include/uapi/linux/thermal.h                  |  1 +
 8 files changed, 50 insertions(+), 6 deletions(-)

-- 
2.25.1