背光设计

Backlight 使用内核中 pwm-backlight 背光驱动，代码见 linux-5.10driversvideobacklightpwm_bl.c。

Panel 驱动可以通过 DTS 获取背光驱动的 device node，然后 backlight API 控制背光。

• backlight_enable() 使能背光

• backlight_update_status() 对背光状态进行更新

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

panel_rgb {
   compatible = "artinchip,aic-general-rgb-panel";

   backlight = <&backlight>;

};  // 为节省篇幅，已省略无关配置

echo 2 > /sys/class/backlight/backlight/brightness