DP83TD510E: link problem of the phy chip in linux

Hello:

I am having problems using DP83TD510E.

Environment:

DP83TD510E works in rmii slave mode. Soc provides a 50Mhz clock to the xi pod.

CRS_DV/RX_DV Pin 18 is configured as CRS_DV (default).

Receiver with tapping at 50 Ω (Recommended).

The id of the phy chip is set to 0.

linux system from the following github link.

https://github.com/nxp-imx/linux-imx/blob/lf-6.1.y/drivers/net/phy/dp83td510.c

My configuration in the device tree is as follows.

&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_enet1>;
	phy-mode = "rmii";
	phy-handle = <&ethphy0>;
	phy-reset-gpios = <&gpio1 1 GPIO_ACTIVE_LOW>;
	phy-reset-duration = <2>;
	status = "okay";
};

&fec2 {
......
	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@0 {
			compatible = "ethernet-phy-id2000.0180";
			reg = <0>;
			clocks = <&clks IMX6UL_CLK_ENET_REF>;
			clock-names = "rmii-ref";
		};
......
	};
};
......
	pinctrl_enet1: enet1grp {
		fsl,pins = <
			MX6UL_PAD_ENET1_RX_EN__ENET1_RX_EN	0x1b0b0
			MX6UL_PAD_ENET1_RX_ER__ENET1_RX_ER	0x1b0b0
			MX6UL_PAD_ENET1_RX_DATA0__ENET1_RDATA00	0x1b0b0
			MX6UL_PAD_ENET1_RX_DATA1__ENET1_RDATA01	0x1b0b0
			MX6UL_PAD_ENET1_TX_EN__ENET1_TX_EN	0x1b0b0
			MX6UL_PAD_ENET1_TX_DATA0__ENET1_TDATA00	0x1b0b0
			MX6UL_PAD_ENET1_TX_DATA1__ENET1_TDATA01	0x1b0b0
			MX6UL_PAD_ENET1_TX_CLK__ENET1_REF_CLK1	0x4001b039
			MX6UL_PAD_GPIO1_IO01__GPIO1_IO01		0xb0
		>;
	};
......

Product test is shown below.

Problem:

The DP83TD510E is always in the Link is down state, and I don't know how to deal with it. The DP83TD510E has been registered.

I tried to test Loopback Modes, but I still don't know how to handle it.

I tried to read the external register, but I didn't know how to read it, something like 0x201.

Thanks.