From: Andrew Morton <akpm@linux-foundation.org>
Date: Fri, 28 Sep 2012 00:20:20 +0000 (+1000)
Subject: pwm_backlight-add-device-tree-support-for-low-threshold-brightness-fix
X-Git-Tag: next-20120928~1^2~135
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1590415b28d62ec167dbfb2a9e0b27f549bbc255;p=karo-tx-linux.git

pwm_backlight-add-device-tree-support-for-low-threshold-brightness-fix

Cc: "Philip, Avinash" <avinashphilip@ti.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Philip, Avinash <avinashphilip@ti.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 4e2991214e54..c02d5ccd6e62 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,15 +14,15 @@ Required properties:
 Optional properties:
   - pwm-names: a list of names for the PWM devices specified in the
                "pwms" property (see PWM binding[0])
-  - low-threshold-brightness: brightness threshold low level. Low threshold
-    brightness set to value so that backlight present on low end of
-    brightness.
-    Some panels, backlight would absent if duty percentage of PWM wave is less
-    than certain level (say 20%). By setting low-threshold-brightness to a
-    value above (percentage of brightness-levels max) 50 (20% of 255, if 255
-    is max). On setting low-threshold-brightness, range of brightness-levels
-    is calculated in a region of low-threshold-brightness to brightness-levels
-    max.
+  - low-threshold-brightness: brightness threshold low level. Sets the lowest
+    brightness value.
+    On some panels the backlight misbehaves if the duty cycle percentage of the
+    PWM wave is less than a certain level (say 20%).  In this example the user
+    can set low-threshold-brightness to a value above 50 (ie, 20% of 255), thus
+    preventing the PWM duty cycle from going too low.
+    On setting low-threshold-brightness the range of brightness levels is
+    calculated in the range low-threshold-brightness to the maximum value in
+    brightness-levels, described above.
 
 [0]: Documentation/devicetree/bindings/pwm/pwm.txt