RK3288 Android 8.1系统uboot logo过渡到kernel logo会花一下

在调试RK3288 Android 8.1系统遇到一个问题：开机启动uboot logo过渡到kernel log的过程中会花掉直到没有显示，再出现kernel logo。

分析：打印串口log时发现，uboot阶段显示一切正常，进入kernel以后就开始花掉了然后变成没有显示了，感觉像是慢慢掉电了一样，再继续查看log发现如下打印：

[ 0.363167] Registered fiq debugger ttyFIQ0

[    0.402908] vcc_sd: regulator get failed, ret=-517

[    0.403332] vcc_lcd: regulator get failed, ret=-517

[    0.403709] vcc_wl: regulator get failed, ret=-517

vcc_lcd是屏电压供电脚，启动内核的时候没有注册上，查看dts节点：

vcc_lcd: vcc-lcd {

compatible = "regulator-fixed";

enable-active-high;

gpio = <&gpio7 3 GPIO_ACTIVE_HIGH>;

pinctrl-names = "default";

pinctrl-0 = <&lcd_en>;

regulator-name = "vcc_lcd";

vin-supply = <&vcc_io>;

};

对比其他dts发现其中少了一个regulator-boot-on;

添加后如下：

vcc_lcd: vcc-lcd {

compatible = "regulator-fixed";

regulator-boot-on;

enable-active-high;

gpio = <&gpio7 3 GPIO_ACTIVE_HIGH>;

pinctrl-names = "default";

pinctrl-0 = <&lcd_en>;

regulator-name = "vcc_lcd";

vin-supply = <&vcc_io>;

};

重新编译kernel，烧录显示正常了。