drm/i915: panel: invert brightness via quirk
A machine may need to invert the panel backlight brightness value. This
patch adds the infrastructure for a quirk to do so.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9f6ba8f..da44999 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -967,14 +967,19 @@
i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
capability is set.
- i915.invert_brightness
+ i915.invert_brightness=
[DRM] Invert the sense of the variable that is used to
set the brightness of the panel backlight. Normally a
- value of 0 indicates backlight switched off, and the
- maximum value sets the backlight to maximum brightness.
- If this parameter is specified, a value of 0 sets the
- backlight to maximum brightness, and the maximum value
- switches the backlight off.
+ brightness value of 0 indicates backlight switched off,
+ and the maximum of the brightness value sets the backlight
+ to maximum brightness. If this parameter is set to 0
+ (default) and the machine requires it, or this parameter
+ is set to 1, a brightness value of 0 sets the backlight
+ to maximum brightness, and the maximum of the brightness
+ value switches the backlight off.
+ -1 -- never invert brightness
+ 0 -- machine default
+ 1 -- force brightness inversion
icn= [HW,ISDN]
Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]