1721badebf
[ Upstream commit ca8fd8c16a8b77dfcf7f6ce52d2c863220693a78 ]
A user complained that the ftsteutates driver was displaying
bogus values since its introduction. This happens because the
sensor measurements need to be scaled in order to produce
meaningful results:
- the fan speed needs to be multiplied by 60 since its in RPS
- the temperature is in degrees celsius and needs an offset of 64
- the voltage is in 1/256 of 3.3V
The offical datasheet says the voltage needs to be divided by 256,
but this is likely an off-by-one-error, since even the BIOS
devides by 255 (otherwise 3.3V could not be measured).
The voltage channels additionally need a board-specific multiplier,
however this can be done by the driver since its board-specific.
The reason the missing scaling of measurements is the way Fujitsu
used this driver when it was still out-of-tree. Back then, all
scaling was done in userspace by libsensors, even the generic one.
Tested on a Fujitsu DS3401-B1.
Fixes: 08426eda58e0 ("hwmon: Add driver for FTS BMC chip "Teutates"")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20221224041855.83981-2-W_Armin@gmx.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.