hwmon: (max6650) Add initial rpm target devicetree documentation

MikeLooijmans · groeck · commit f9f8b33d3730 · 2016-09-08T21:34:17.000-07:00
Add devicetree property for early initialization of the fan controller
to prevent overheating, for example when resetting the board while the
fan was completely turned off.

Signed-off-by: Mike Looijmans &lt;mike.looijmans@topic.nl&gt;
Acked-by: Rob Herring &lt;robh@kernel.org&gt;
Signed-off-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
diff --git a/Documentation/devicetree/bindings/hwmon/max6650.txt b/Documentation/devicetree/bindings/hwmon/max6650.txt
@@ -13,11 +13,16 @@ Optional properties, default is to retain the chip's current setting:
 - maxim,fan-prescale  : Pre-scaling value, as per datasheet [1]. Lower values
 			allow more fine-grained control of slower fans.
 			Valid: 1, 2, 4, 8, 16.
+- maxim,fan-target-rpm: Initial requested fan rotation speed. If specified, the
+			driver selects closed-loop mode and the requested speed.
+			This ensures the fan is already running before userspace
+			takes over.
 
 Example:
 	fan-max6650: max6650@1b {
 		reg = <0x1b>;
 		compatible = "maxim,max6650";
 		maxim,fan-microvolt = <12000000>;
 		maxim,fan-prescale = <4>;
+		maxim,fan-target-rpm = <1200>;
 	};
