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ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

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Set #pwm-cells to the default 3 to gain access to the parameter
which allows inverting the PWM signal. This is useful to specify
a backlight which has its highest brightness at 0.

With the change to use the PWM with inverted polarity the PWM signal
is inverted to how it was before this patch.
This changes the meaning of the values in the brightness-levels
property. I.e. the duty-cycle changes from x/255 to (255-x)/255.
Keeping the brightness-levels will then have a big brightness
jump from 0 to 127 duty cycle, the other 6 steps will then be
barely noticeable.

Change the brightness-levels to provide the same brightness-levels
as before.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Max Krummenacher
2022-05-13 12:26:14 +02:00
committed by Shawn Guo
parent c77c5b25c1
commit 14092ffbd7
1 changed files with 4 additions and 4 deletions
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8
arch/arm/boot/dts/imx6qdl-colibri.dtsi
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@@ -6,6 +6,7 @@
*/
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pwm/pwm.h>
/ {
model = "Toradex Colibri iMX6DL/S Module";
@@ -13,13 +14,13 @@ / {
backlight: backlight {
compatible = "pwm-backlight";
brightness-levels = <0 127 191 223 239 247 251 255>;
default-brightness-level = <1>;
brightness-levels = <0 4 8 16 32 64 128 255>;
default-brightness-level = <6>;
enable-gpios = <&gpio3 26 GPIO_ACTIVE_HIGH>; /* Colibri BL_ON */
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpio_bl_on>;
power-supply = <&reg_module_3v3>;
pwms = <&pwm3 0 5000000>;
pwms = <&pwm3 0 5000000 PWM_POLARITY_INVERTED>;
status = "disabled";
};
@@ -620,7 +621,6 @@ &pwm2 {
/* Colibri PWM<A> */
&pwm3 {
#pwm-cells = <2>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_pwm3>;
status = "disabled";