1pwm-backlight bindings 2 3Required properties: 4 - compatible: "pwm-backlight" 5 - pwms: OF device-tree PWM specification (see PWM binding[0]) 6 - power-supply: regulator for supply voltage 7 8Optional properties: 9 - pwm-names: a list of names for the PWM devices specified in the 10 "pwms" property (see PWM binding[0]) 11 - enable-gpios: contains a single GPIO specifier for the GPIO which enables 12 and disables the backlight (see GPIO binding[1]) 13 - post-pwm-on-delay-ms: Delay in ms between setting an initial (non-zero) PWM 14 and enabling the backlight using GPIO. 15 - pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO 16 and setting PWM value to 0. 17 - brightness-levels: Array of distinct brightness levels. Typically these 18 are in the range from 0 to 255, but any range starting at 19 0 will do. The actual brightness level (PWM duty cycle) 20 will be interpolated from these values. 0 means a 0% duty 21 cycle (darkest/off), while the last value in the array 22 represents a 100% duty cycle (brightest). 23 - default-brightness-level: The default brightness level (index into the 24 array defined by the "brightness-levels" property). 25 - num-interpolated-steps: Number of interpolated steps between each value 26 of brightness-levels table. This way a high 27 resolution pwm duty cycle can be used without 28 having to list out every possible value in the 29 brightness-level array. 30 31[0]: Documentation/devicetree/bindings/pwm/pwm.txt 32[1]: Documentation/devicetree/bindings/gpio/gpio.txt 33 34Example: 35 36 backlight { 37 compatible = "pwm-backlight"; 38 pwms = <&pwm 0 5000000>; 39 40 brightness-levels = <0 4 8 16 32 64 128 255>; 41 default-brightness-level = <6>; 42 43 power-supply = <&vdd_bl_reg>; 44 enable-gpios = <&gpio 58 0>; 45 post-pwm-on-delay-ms = <10>; 46 pwm-off-delay-ms = <10>; 47 }; 48 49Example using num-interpolation-steps: 50 51 backlight { 52 compatible = "pwm-backlight"; 53 pwms = <&pwm 0 5000000>; 54 55 brightness-levels = <0 2048 4096 8192 16384 65535>; 56 num-interpolated-steps = <2048>; 57 default-brightness-level = <4096>; 58 59 power-supply = <&vdd_bl_reg>; 60 enable-gpios = <&gpio 58 0>; 61 }; 62