PWM Backlight

panel_rgb {
    ...
    backlight = <&backlight>;

}

backlight: backlight {
    compatible = "pwm-backlight";
    /* pwm node name; pwm device No.; period_ns; pwm_polarity */
    pwms = <&pwm 2 1000000 0>;
    brightness-levels = <0 10 20 30 40 50 60 70 80 90 100>;
    default-brightness-level = <8>;
    status = "okay";
};

&pwm {
    status = "okay";
    pinctrl-names = "default";
    pinctrl-0 = <&pwm2_pins_b>;
    /* mode: up-count, down-count, up-down-count
       action: none, low, high, inverse */

    pwm2 {
        aic,mode = "up-count";
        aic,tb-clk-rate = <24000000>;
        /*            CBD,    CBU,    CAD,    CAU,    PRD,   ZRO */
        aic,action0 = "none", "none", "none", "high", "low", "none";
        aic,action1 = "none", "none", "none", "low", "high", "none";
        aic,default-level = <0>;
        aic,rise-edge-delay = <10>;
        aic,fall-edge-delay = <10>;
        status = "okay";
    };

};

背光控制依赖 PWM 模块，详细配置可参考 PWM 使用指南。