video/backlight: document sysfs interface

Date and KernelVersion may be wrong because the backlight
interface was introduced before git initial import.

Cc:Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight
new file mode 100644 (file)
index 0000000..4d637e1
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-class-backlight
@@ -0,0 +1,36 @@
+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