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Diffstat (limited to 'Documentation/ABI/stable/sysfs-class-backlight')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-class-backlight | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight new file mode 100644 index 0000000000..023fb52645 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-class-backlight @@ -0,0 +1,57 @@ +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. |