5601ef91fb
The driver registers a thermal zone for each transceiver module and
tries to set the trip point temperatures according to the thresholds
read from the transceiver. If a threshold cannot be read or if a
transceiver is unplugged, the trip point temperature is set to zero,
which means that it is disabled as far as the thermal subsystem is
concerned.
A recent change in the thermal core made it so that such trip points are
no longer marked as disabled, which lead the thermal subsystem to
incorrectly set the associated cooling devices to the their maximum
state [1]. A fix to restore this behavior was merged in commit
f1b80a3878b2 ("thermal: core: Restore behavior regarding invalid trip
points"). However, the thermal maintainer suggested to not rely on this
behavior and instead always register a valid array of trip points [2].
Therefore, create a static array of trip points with sane defaults
(suggested by Vadim) and register it with the thermal zone of each
transceiver module. User space can choose to override these defaults
using the thermal zone sysfs interface since these files are writeable.
Before:
$ cat /sys/class/thermal/thermal_zone11/type
mlxsw-module11
$ cat /sys/class/thermal/thermal_zone11/trip_point_*_temp
65000
75000
80000
After:
$ cat /sys/class/thermal/thermal_zone11/type
mlxsw-module11
$ cat /sys/class/thermal/thermal_zone11/trip_point_*_temp
55000
65000
80000
Also tested by reverting commit f1b80a3878b2 ("thermal: core: Restore
behavior regarding invalid trip points") and making sure that the
associated cooling devices are not set to their maximum state.
[1] https://lore.kernel.org/linux-pm/ZA3CFNhU4AbtsP4G@shredder/
[2] https://lore.kernel.org/linux-pm/f78e6b70-a963-c0ca-a4b2-0d4c6aeef1fb@linaro.org/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 Restructured Text 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.