Boot speed of the imx.8plus. Why is the kernel slow to initialize emmc？

[chen-wust]

To make the processor boot faster, I changed the emmc read mode from the default mode（HS 52M） to HS200(200M).I achieved this by modifying the device tree of uboot：Add the following properties.

mmc-hs200-1_8v;

In uboot, emmc read speed increased from 30M/S to 60M/S.

However, this affects the kernel boot speed, and the kernel initializing emmc is one second slower, making the overall boot speed slower.

May I ask what causes this problem? I really hope to get your help and reply.

May I ask what causes this problem? Can you give some suggestions to solve this problem? I really hope to get your help and reply

[chen-wust]

uboot emmc dts：

&usdhc2 {
	pinctrl-names = "default", "state_100mhz", "state_200mhz";
	pinctrl-0 = <&pinctrl_usdhc2>;
	pinctrl-1 = <&pinctrl_usdhc2_100mhz>;
	pinctrl-2 = <&pinctrl_usdhc2_200mhz>;
	vmmc-supply = <&reg_usdhc2_vmmc>;
	bus-width = <4>;
        broken-cd;
	status = "okay";
};

&usdhc3 {
	pinctrl-names = "default", "state_100mhz", "state_200mhz";
	pinctrl-0 = <&pinctrl_usdhc3>,<$pinctrl_usdhc3_gpio>;
	pinctrl-1 = <&pinctrl_usdhc3_100mhz>,<$pinctrl_usdhc3_gpio>;
	pinctrl-2 = <&pinctrl_usdhc3_200mhz>,<$pinctrl_usdhc3_gpio>;
	bus-width = <8>;
	non-removable;
        mmc-hs2-1_2v;//This is the property I added
	status = "okay";
};

kernel emmc dts

&usdhc2 {
	pinctrl-names = "default", "state_100mhz", "state_200mhz";
	pinctrl-0 = <&pinctrl_usdhc2>;
	pinctrl-1 = <&pinctrl_usdhc2_100mhz>;
	pinctrl-2 = <&pinctrl_usdhc2_200mhz>;
	//cd-gpios = <&gpio4 26 GPIO_ACTIVE_LOW>;
        //broken-cd;
	vmmc-supply = <&reg_usdhc2_vmmc>;
        no-1-8v;
        disable-wp;
	bus-width = <4>;
	status = "okay";
};

&usdhc3 {
	pinctrl-names = "default", "state_100mhz", "state_200mhz";
	pinctrl-0 = <&pinctrl_usdhc3>;
	pinctrl-1 = <&pinctrl_usdhc3_100mhz>;
	pinctrl-2 = <&pinctrl_usdhc3_200mhz>;
	bus-width = <8>;
        no-sd;
        no-sdio;
	non-removable;
        mmc-hs400-1_8v;
        mmc-hs400-emhanced-strobe;
	status = "okay";
};