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dt-bindings: pwm-backlight: Add a num-interpolation-steps property 

The num-interpolated-steps property specifies the number of
interpolated steps between each value of brightness-level table. This is
useful for high resolution PWMs to not have to list out every possible
value in the brightness-level array.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Enric Balletbo i Serra 2018-04-09 10:33:31 +02:00 committed by Lee Jones
parent 573fe6d1c2
commit 1e5e7cc794
1 changed files with 19 additions and 0 deletions
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19
Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
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@ -21,6 +21,11 @@ Optional properties:
and enabling the backlight using GPIO.
- pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO
and setting PWM value to 0.
- num-interpolated-steps: Number of interpolated steps between each value
of brightness-levels table. This way a high
resolution pwm duty cycle can be used without
having to list out every possible value in the
brightness-level array.
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
[1]: Documentation/devicetree/bindings/gpio/gpio.txt
@ -39,3 +44,17 @@ Example:
post-pwm-on-delay-ms = <10>;
pwm-off-delay-ms = <10>;
};
Example using num-interpolation-steps:
backlight {
compatible = "pwm-backlight";
pwms = <&pwm 0 5000000>;
brightness-levels = <0 2048 4096 8192 16384 65535>;
num-interpolated-steps = <2048>;
default-brightness-level = <4096>;
power-supply = <&vdd_bl_reg>;
enable-gpios = <&gpio 58 0>;
};