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authorHans de Goede2017-01-29 14:42:52 +0100
committerJacek Anaszewski2017-01-29 19:59:42 +0100
commit0cb8eb30d425d2d2ae28ab630596c44a158784c4 (patch)
tree8f715703e9e929f615160d3b326f5fff2708d670 /Documentation/ABI
parentcbe99c538d1776009e8710755bb6e726f7fffa9b (diff)
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>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-class-led17
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 491cdeedc195..5f67f7ab277b 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -23,6 +23,23 @@ Description:
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
KernelVersion: 2.6.17