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2017-01-29leds: class: Add new optional brightness_hw_changed attributeHans de Goede
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>
2016-11-22cleanup LED documentation and make it match realityPavel Machek
sysfs-class-led fails to mention some important details. Also fix led vs LED and english. Signed-off-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
2016-08-29Documentation: move oneshot trigger attributes documentation to ABIRafał Miłecki
Documentation of sysfs interface should be in ABI in the first place. This moves relevant part of documentation and mentions where to look for it. Fix trivial typos whilst we are at it. Signed-off-by: Rafał Miłecki <rafal@milecki.pl> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-01-13leds: add output inversion option to backlight triggerJanusz Krzysztofik
Extend the LED backlight tirgger driver with an option that allows for inverting the trigger output polarity. With the invertion option provided, I (ab)use the backlight trigger for driving a LED that indicates LCD display blank condtition on my Amstrad Delta videophone. Since the machine has no dedicated power LED, it was not possible to distinguish if the display was blanked, or the machine was turned off, without touching it. The invert sysfs control is patterned after a similiar function of the GPIO trigger driver. [akpm@linux-foundation.org: make output match input, tighten input checking] [akpm@linux-foundation.org: make output match input, tighten input checking] Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> Cc: Paul Mundt <lethal@linux-sh.org> Acked-by: Richard Purdie <richard.purdie@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-08-28led: document sysfs interfaceCorentin Chary
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>