linux/Documentation/leds
Hans de Goede 0cb8eb30d4 leds: class: Add new optional brightness_hw_changed attribute
Some LEDs may have their brightness level changed autonomously
(outside of kernel control) by hardware / firmware. This commit
adds support for an optional brightness_hw_changed attribute to
signal such changes to userspace (if a driver can detect them):

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.

Drivers which want to support this, simply add LED_BRIGHT_HW_CHANGED to
their flags field and call led_classdev_notify_brightness_hw_changed()
with the hardware set brightness when they detect a hardware / firmware
triggered brightness change.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
2017-01-29 19:59:42 +01:00
..
00-INDEX Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
leds-blinkm.txt LEDS: add BlinkM RGB LED driver, documentation and update MAINTAINERS 2012-07-24 16:00:51 +08:00
leds-class-flash.txt Documentation: leds: Add description of v4l2-flash sub-device 2015-06-10 13:46:28 -07:00
leds-class.txt leds: class: Add new optional brightness_hw_changed attribute 2017-01-29 19:59:42 +01:00
leds-lm3556.txt Documentation: leds: Fix a typo 2013-08-26 17:22:12 -07:00
leds-lp55xx.txt leds: lp5523: Support LED MUX configuration on running a pattern 2014-01-27 17:28:48 -08:00
leds-lp3944.txt Documentation: leds: Fix a typo 2013-08-26 17:22:12 -07:00
leds-lp5521.txt Documentation: leds-lp5521,lp5523: update device attribute information 2013-08-26 17:22:13 -07:00
leds-lp5523.txt leds/leds-lp5523.txt: make documentation match reality 2016-11-22 12:07:02 +01:00
leds-lp5562.txt leds: lp55xx: configure the clock detection 2013-04-01 11:04:53 -07:00
leds-mlxcpld.txt leds: add driver for Mellanox systems LEDs 2016-09-15 16:49:39 +02:00
ledtrig-oneshot.txt Documentation: move oneshot trigger attributes documentation to ABI 2016-08-29 15:06:32 +02:00
ledtrig-transient.txt leds: add new transient trigger for one shot timer activation 2012-05-29 16:22:32 -07:00
ledtrig-usbport.txt usb: core: Introduce a USB port LED trigger 2016-09-27 12:20:17 +02:00
uleds.txt leds: Introduce userspace LED class driver 2016-11-22 12:07:02 +01:00