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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 compatible with
- FB_BLANK_* from fb.h
- - 0 (FB_BLANK_UNBLANK) : power on.
- - 4 (FB_BLANK_POWERDOWN) : 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. Due
- to implementation differences in hardware this may not
- match the value in 'brightness'. For example some hardware
- may treat blanking differently or have custom power saving
- features. Userspace should generally use the values in
- 'brightness' to make decisions.
- 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.
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