Document the global brightness attribute for the Turris Omnia LED
controller.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
--- /dev/null
+What: /sys/class/leds/<led>/device/brightness
+Date: July 2020
+KernelVersion: 5.9
+Contact: Marek Behún <marek.behun@nic.cz>
+Description: (RW) On the front panel of the Turris Omnia router there is also
+ a button which can be used to control the intensity of all the
+ LEDs at once, so that if they are too bright, user can dim them.
+
+ The microcontroller cycles between 8 levels of this global
+ brightness (from 100% to 0%), but this setting can have any
+ integer value between 0 and 100. It is therefore convenient to be
+ able to change this setting from software.
+
+ Format: %i