| 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. |
