ARM: dts: droid4: Configure LED backlight for lm3532

With the LED backlight changes merged, we still need the dts configured
to have backlight working for droid4. Based on an earlier patch from
Pavel Machek <[email protected]>, let's configure the backlight but update
the value range to be more usable.

We have a range of 256 register values split into 8 steps, so we can
generate the brightness levels backwards with:

$ for i in 0 1 2 3 4 5 6 7; do echo "255 - ${i} * (256 / 8)" | bc; done

To avoid more confusion why the LCD backlight is still not on, let's
also enable LED backlight as a loadable module for omap2plus_defconfig.

Cc: Merlijn Wajer <[email protected]>
Cc: Pavel Machek <[email protected]>
Reviewed-by: Sebastian Reichel <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>

Author: tmlind

arch/arm/boot/dts/motorola-mapphone-common.dtsi

@@ -182,6 +182,14 @@
 		pwm-names = "enable", "direction";
 		direction-duty-cycle-ns = <10000000>;
 	};
+
+	backlight: backlight {
+		compatible = "led-backlight";
+
+		leds = <&backlight_led>;
+		brightness-levels = <31 63 95 127 159 191 223 255>;
+		default-brightness-level = <6>;
+	};
 };
 
 &dss {
@@ -205,6 +213,8 @@
 		vddi-supply = <&lcd_regulator>;
 		reset-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>;	/* gpio101 */
 
+		backlight = <&backlight>;
+
 		width-mm = <50>;
 		height-mm = <89>;
 
@@ -393,12 +403,11 @@
 		ramp-up-us = <1024>;
 		ramp-down-us = <8193>;
 
-		led@0 {
+		backlight_led: led@0 {
 			reg = <0>;
 			led-sources = <2>;
 			ti,led-mode = <0>;
 			label = ":backlight";
-			linux,default-trigger = "backlight";
 		};
 
 		led@1 {

arch/arm/configs/omap2plus_defconfig

@@ -375,6 +375,7 @@ CONFIG_BACKLIGHT_GENERIC=m
 CONFIG_BACKLIGHT_PWM=m
 CONFIG_BACKLIGHT_PANDORA=m
 CONFIG_BACKLIGHT_GPIO=m
+CONFIG_BACKLIGHT_LED=m
 CONFIG_FRAMEBUFFER_CONSOLE=y
 CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
 CONFIG_LOGO=y