diff options
Diffstat (limited to 'Documentation/ABI/testing/sysfs-class-led')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-led | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led index 86ace287d48b..5f67f7ab277b 100644 --- a/Documentation/ABI/testing/sysfs-class-led +++ b/Documentation/ABI/testing/sysfs-class-led @@ -4,16 +4,41 @@ KernelVersion: 2.6.17 Contact: Richard Purdie <rpurdie@rpsys.net> Description: Set the brightness of the LED. Most LEDs don't - have hardware brightness support so will just be turned on for + have hardware brightness support, so will just be turned on for non-zero brightness settings. The value is between 0 and /sys/class/leds/<led>/max_brightness. + Writing 0 to this file clears active trigger. + + Writing non-zero to this file while trigger is active changes the + top brightness trigger is going to use. + What: /sys/class/leds/<led>/max_brightness Date: March 2006 KernelVersion: 2.6.17 Contact: Richard Purdie <rpurdie@rpsys.net> Description: - Maximum brightness level for this led, default is 255 (LED_FULL). + Maximum brightness level for this LED, default is 255 (LED_FULL). + + If the LED does not support different brightness levels, this + should be 1. + +What: /sys/class/leds/<led>/brightness_hw_changed +Date: January 2017 +KernelVersion: 4.11 +Description: + Last hardware set brightness level for this LED. Some LEDs + may be changed autonomously by hardware/firmware. Only LEDs + where this happens and the driver can detect this, will have + this file. + + This file supports poll() to detect when the hardware changes + the brightness. + + Reading this file will return the last brightness level set + by the hardware, this may be different from the current + brightness. Reading this file when no hw brightness change + event has happened will return an ENODATA error. What: /sys/class/leds/<led>/trigger Date: March 2006 @@ -21,7 +46,7 @@ KernelVersion: 2.6.17 Contact: Richard Purdie <rpurdie@rpsys.net> Description: Set the trigger for this LED. A trigger is a kernel based source - of led events. + of LED events. You can change triggers in a similar manner to the way an IO scheduler is chosen. Trigger specific parameters can appear in /sys/class/leds/<led> once a given trigger is selected. For |