• 如果使用pwm并且配置compatible = "pwm-backlight"(与pwm_bl 驱动进行匹配);会受到驱动影响，屏幕初始化失败有可能导致背光的电源强制关闭bl_power = 4

    DRM 面板驱动把背光禁用了

  • 在设备树的树根/下配置backlight节点

    // LCD Backlight
backlight: backlight {
	compatible = "pwm-backlight";
	pwms = <&pwm3 0 50000 0>;
	brightness-levels = <0 20 40 60 80 100 200 255>;
	default-brightness-level = <7>;
	status = "okay";
};

  • 配置pwm3的复用(pinctrl子系统)

    &pwm3 {
	status = "okay";
	pinctrl-0 = <&pwm3m1_pins>;
};

  • GPIO测试背光

    echo 40 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio40/direction
echo 1 > /sys/class/gpio/gpio40/value