linux-imx/Documentation/ABI/testing/sysfs-class-led
Takashi Iwai 8f2244c9af leds: class: Don't expose color sysfs entry
The commit c7d80059b0 ("leds: class: Store the color index in struct
led_classdev") introduced a new sysfs entry "color" that is commonly
created for the led classdev.  Unfortunately, this conflicts with the
"color" sysfs entry of already existing drivers such as Logitech HID
or System76 ACPI drivers.  The driver probe fails due to the conflict,
hence it leads to a severe regression with the missing keyboard, for
example.

This patch reverts partially the change in the commit above for
removing the led class color sysfs entries again for addressing the
regressions.  The newly introduced led_classdev.color field is kept as
it's already used by other driver.

Fixes: c7d80059b0 ("leds: class: Store the color index in struct led_classdev")
Reported-by: Johannes Penßel <johannes.penssel@gmail.com>
Closes: https://lore.kernel.org/r/b5646db3-acff-45aa-baef-df3f660486fb@gmail.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218045
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218155
Link: https://bugzilla.suse.com/show_bug.cgi?id=1217172
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20231121162359.9332-1-tiwai@suse.de
Signed-off-by: Lee Jones <lee@kernel.org>
2023-11-22 11:46:03 +00:00

2.6 KiB

What: /sys/class/leds//brightness Date: March 2006 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 non-zero brightness settings.

	.. Note::

	  For multicolor LEDs, writing to this file will update all
	  LEDs within the group to a calculated percentage of what
	  each color LED intensity is set to.

	  The percentage is calculated for each grouped LED via
	  the equation below::

	    led_brightness = brightness * multi_intensity/max_brightness

	  For additional details please refer to
	  Documentation/leds/leds-class-multicolor.rst.

	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//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).

	If the LED does not support different brightness levels, this
	should be 1.

What: /sys/class/leds//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//trigger Date: March 2006 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.

	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
	their documentation see `sysfs-class-led-trigger-*`.

What: /sys/class/leds//inverted Date: January 2011 KernelVersion: 2.6.38 Contact: Richard Purdie rpurdie@rpsys.net Description: Invert the LED on/off state. This parameter is specific to gpio and backlight triggers. In case of the backlight trigger, it is useful when driving a LED which is intended to indicate a device in a standby like state.