tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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led: document sysfs interface

Also fix Documentation/led-class.txt, the acceptable
range of values for brightness is 0-max_brightness, not 0-255.

Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Len Brown <len.brown@intel.com>

authored by

Corentin Chary and committed by
Len Brown 5f634c65 243ca3e4

+33 -4
+28
Documentation/ABI/testing/sysfs-class-led
··· 1 + What: /sys/class/leds/<led>/brightness 2 + Date: March 2006 3 + KernelVersion: 2.6.17 4 + Contact: Richard Purdie <rpurdie@rpsys.net> 5 + Description: 6 + Set the brightness of the LED. Most LEDs don't 7 + have hardware brightness support so will just be turned on for 8 + non-zero brightness settings. The value is between 0 and 9 + /sys/class/leds/<led>/max_brightness. 10 + 11 + What: /sys/class/leds/<led>/max_brightness 12 + Date: March 2006 13 + KernelVersion: 2.6.17 14 + Contact: Richard Purdie <rpurdie@rpsys.net> 15 + Description: 16 + Maximum brightness level for this led, default is 255 (LED_FULL). 17 + 18 + What: /sys/class/leds/<led>/trigger 19 + Date: March 2006 20 + KernelVersion: 2.6.17 21 + Contact: Richard Purdie <rpurdie@rpsys.net> 22 + Description: 23 + Set the trigger for this LED. A trigger is a kernel based source 24 + of led events. 25 + You can change triggers in a similar manner to the way an IO 26 + scheduler is chosen. Trigger specific parameters can appear in 27 + /sys/class/leds/<led> once a given trigger is selected. 28 +
+5 -4
Documentation/leds-class.txt
··· 1 + 1 2 LED handling under Linux 2 3 ======================== 3 4 ··· 6 5 handled by the input subsystem and the led class is *not* needed. 7 6 8 7 In its simplest form, the LED class just allows control of LEDs from 9 - userspace. LEDs appear in /sys/class/leds/. The brightness file will 10 - set the brightness of the LED (taking a value 0-255). Most LEDs don't 11 - have hardware brightness support so will just be turned on for non-zero 12 - brightness settings. 8 + userspace. LEDs appear in /sys/class/leds/. The maximum brightness of the 9 + LED is defined in max_brightness file. The brightness file will set the brightness 10 + of the LED (taking a value 0-max_brightness). Most LEDs don't have hardware 11 + brightness support so will just be turned on for non-zero brightness settings. 13 12 14 13 The class also introduces the optional concept of an LED trigger. A trigger 15 14 is a kernel based source of led events. Triggers can either be simple or