linux/Documentation/hwmon/sch5627.rst
Armin Wolf e09b750526 hwmon: (sch5627) Document behaviour of limit registers
The values of the limit registers affect the fan speed in a
particular way. Document this behaviour so that future users
can exploit it if required.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20230907052639.16491-6-W_Armin@gmx.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2023-10-27 07:27:24 -07:00

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Kernel driver sch5627
=====================
Supported chips:
* SMSC SCH5627
Prefix: 'sch5627'
Addresses scanned: none, address read from Super I/O config space
Datasheet: Application Note available upon request
Author: Hans de Goede <hdegoede@redhat.com>
Description
-----------
SMSC SCH5627 Super I/O chips include complete hardware monitoring
capabilities. They can monitor up to 5 voltages, 4 fans and 8 temperatures.
In addition, the SCH5627 exports data describing which temperature sensors
affect the speed of each fan. Setting pwmX_auto_channels_temp to 0 forces
the corresponding fan to full speed until another value is written.
The SMSC SCH5627 hardware monitoring part also contains an integrated
watchdog. In order for this watchdog to function some motherboard specific
initialization most be done by the BIOS, so if the watchdog is not enabled
by the BIOS the sch5627 driver will not register a watchdog device.
The hardware monitoring part of the SMSC SCH5627 is accessed by talking
through an embedded microcontroller. An application note describing the
protocol for communicating with the microcontroller is available upon
request. Please mail me if you want a copy.
Controlling fan speed
---------------------
The SCH5627 allows for partially controlling the fan speed. If a temperature
channel excedes tempX_max, all fans are forced to maximum speed. The same is not
true for tempX_crit, presumably some other measures to cool down the system are
take in this case.
In which way the value of fanX_min affects the fan speed is currently unknown.