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>

diff --git a/Documentation/hwmon/sch5627.rst b/Documentation/hwmon/sch5627.rst
index ecb4fc84d0451a1940115dfe9a4d480cc0e5af5a..8639dff234fcec323b385c439a41277deb65de31 100644 (file)
--- a/Documentation/hwmon/sch5627.rst
+++ b/Documentation/hwmon/sch5627.rst
@@ -33,3 +33,13 @@ 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.