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Daniel Lezcano f67cf45dee Revert "thermal: core: Don't update trip points inside the hysteresis range" 
It has been reported the commit cf3986f8c0 introduced a regression
when the temperature is wavering in the hysteresis region. The
mitigation stops leading to an uncontrolled temperature increase until
reaching the critical trip point.

Here what happens:

 * 'throttle' is when the current temperature is greater than the trip
   point temperature
 * 'target' is the mitigation level
 * 'passive' is positive when there is a mitigation, zero otherwise
 * these values are computed in the step_wise governor

Configuration:

 trip point 1: temp=95°C, hyst=5°C (passive)
 trip point 2: temp=115°C, hyst=0°C (critical)
 governor: step_wise

 1. The temperature crosses the way up the trip point 1 at 95°C

   - trend=raising
   - throttle=1, target=1
   - passive=1
   - set_trips: low=90°C, high=115°C

 2. The temperature decreases but stays in the hysteresis region at
    93°C

   - trend=dropping
   - throttle=0, target=0
   - passive=1

   Before cf3986f8c0
   - set_trips: low=90°C, high=95°C

   After cf3986f8c0
   - set_trips: low=90°C, high=115°C

 3. The temperature increases a bit but stays in the hysteresis region
    at 94°C (so below the trip point 1 temp 95°C)

   - trend=raising
   - throttle=0, target=0
   - passive=1

   Before cf3986f8c0
   - set_trips: low=90°C, high=95°C

   After cf3986f8c0
   - set_trips: low=90°C, high=115°C

 4. The temperature decreases but stays in the hysteresis region at
    93°C

   - trend=dropping
   - throttle=0, target=THERMAL_NO_TARGET
   - passive=0

   Before cf3986f8c0
   - set_trips: low=90°C, high=95°C

   After cf3986f8c0
   - set_trips: low=90°C, high=115°C

At this point, the 'passive' value is zero, there is no mitigation,
the temperature is in the hysteresis region, the next trip point is
115°C. As 'passive' is zero, the timer to monitor the thermal zone is
disabled. Consequently if the temperature continues to increase, no
mitigation will happen and it will reach the 115°C trip point and
reboot.

Before the optimization, the high boundary would have been 95°C, thus
triggering the mitigation again and rearming the polling timer.

The optimization make sense but given the current implementation of
the step_wise governor collaborating via this 'passive' flag with the
core framework it can not work.

From a higher perspective it seems like there is a problem between the
governor which sets a variable to be used by the core framework. That
sounds akward and it would make much more sense if the core framework
controls the governor and not the opposite. But as the devil hides in
the details, there are some subtilities to be addressed before.

Elaborating those would be out of the scope this changelog. So let's
stay simple and revert the change first to fixup all broken mobile
platforms.

This reverts commit cf3986f8c0 ("thermal: core: Don't update trip
points inside the hysteresis range") and takes a conflict with commit
0c0c4740c9 ("0c0c4740c9d2 thermal: trip: Use for_each_trip() in
__thermal_zone_set_trips()") in drivers/thermal/thermal_trip.c into
account.

Fixes: cf3986f8c0 ("thermal: core: Don't update trip points inside the hysteresis range")
Reported-by: Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Cc: 6.7+ <stable@vger.kernel.org> # 6.7+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2024-03-26 13:18:13 +01:00
arch EFI fixes for v6.9 #2 2024-03-24 13:54:06 -07:00
block vfs-6.9-rc1.fixes 2024-03-18 09:15:50 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
Documentation A set of x86 fixes: 2024-03-24 11:13:56 -07:00
drivers Revert "thermal: core: Don't update trip points inside the hysteresis range" 2024-03-26 13:18:13 +01:00
fs A patch to minimize blockage when processing very large batches of 2024-03-22 11:15:45 -07:00
include powerpc updates for 6.9 #2 2024-03-23 09:21:26 -07:00
init RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
io_uring io_uring/sqpoll: early exit thread if task_context wasn't allocated 2024-03-18 20:22:42 -06:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel dma-mapping fixes for Linux 6.9 2024-03-24 10:45:31 -07:00
lib hardening fixes for v6.9-rc1 2024-03-23 08:43:21 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
net Including fixes from CAN, netfilter, wireguard and IPsec. 2024-03-21 14:50:39 -07:00
rust Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts LoongArch changes for v6.9 2024-03-22 10:22:45 -07:00
security - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
sound sound fixes #2 for 6.9-rc2 2024-03-22 09:44:19 -07:00
tools RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM Xen and pfncache changes for 6.9: 2024-03-11 10:42:55 -04:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap Char/Misc and other driver subsystem updates for 6.9-rc1 2024-03-21 13:21:31 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Not a ton of stuff happening in the clk framework in this pull request. We got 2024-03-15 11:48:01 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS RISC-V Patches for the 6.9 Merge Window 2024-03-22 10:41:13 -07:00
Makefile Linux 6.9-rc1 2024-03-24 14:10:05 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.