sysfs-class-backlight
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What: /sys/class/backlight/<backlight>/bl_power
Date: April 2005
KernelVersion: 2.6.12
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Control BACKLIGHT power, values are FB_BLANK_* from fb.h
- FB_BLANK_UNBLANK (0) : power on.
- FB_BLANK_POWERDOWN (4) : power off
Users: HAL
What: /sys/class/backlight/<backlight>/brightness
Date: April 2005
KernelVersion: 2.6.12
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Control the brightness for this <backlight>. Values
are between 0 and max_brightness. This file will also
show the brightness level stored in the driver, which
may not be the actual brightness (see actual_brightness).
Users: HAL
What: /sys/class/backlight/<backlight>/actual_brightness
Date: March 2006
KernelVersion: 2.6.17
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Show the actual brightness by querying the hardware.
Users: HAL
What: /sys/class/backlight/<backlight>/max_brightness
Date: April 2005
KernelVersion: 2.6.12
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Maximum brightness for <backlight>.
Users: HAL
What: /sys/class/backlight/<backlight>/type
Date: September 2010
KernelVersion: 2.6.37
Contact: Matthew Garrett <mjg@redhat.com>
Description:
The type of interface controlled by <backlight>.
"firmware": The driver uses a standard firmware interface
"platform": The driver uses a platform-specific interface
"raw": The driver controls hardware registers directly
In the general case, when multiple backlight
interfaces are available for a single device, firmware
control should be preferred to platform control should
be preferred to raw control. Using a firmware
interface reduces the probability of confusion with
the hardware and the OS independently updating the
backlight state. Platform interfaces are mostly a
holdover from pre-standardisation of firmware
interfaces.