需要配置target/linux/ramips/dts/下相关文件（mt7620a.dtsi，MT7620a.dts）。 在mt7620a.dtsi中，palmbus@10000000下已经定义好了uart和uartlite，但是uart的status是disabled：
uart@500 { compatible = "ralink,mt7620a-uart", "ralink,rt2880-uart", "ns16550a"; reg = <0x500 0x100>; resets = <&rstctrl 12>; reset-names = "uart"; interrupt-parent = <&intc>; interrupts = <5>; reg-shift = <2>; status = "disabled"; };在 pinctrl {中定义了uart各种复用的功能，但具体使用哪一种功能没有定义：
pcm_i2s_pins: pcm_i2s { pcm_i2s { ralink,group = "uartf"; ralink,function = "pcm i2s"; }; }; uartf_gpio_pins: uartf_gpio { uartf_gpio { ralink,group = "uartf"; ralink,function = "gpio uartf"; }; };以下是需要在MT7620a.dts修改的地方，MT7620a.dts中include了mt7620a.dtsi，因为要使能uartf，console如果仍然使用uartlite，需要修改
chosen { bootargs = "console=ttyS1,57600"; };在 palmbus@10000000 {中添加uart enable
uart@500 { status = "okay"; };在pinctrl {中配置uartf复用的功能
pinctrl { state_default: pinctrl0 { gpio { ralink,group = "i2c"; ralink,function = "gpio"; }; uartf_gpio { ralink,group = "uartf"; ralink,function = "gpio uartf"; }; }; };完整的MT7620a.dts内容如下：
/dts-v1/; /include/ "mt7620a.dtsi" / { compatible = "ralink,mt7620a-eval-board", "ralink,mt7620a-soc"; model = "Ralink MT7620a + MT7610e evaluation board"; chosen { bootargs = "console=ttyS1,57600"; }; palmbus@10000000 { spi@b00 { status = "okay"; m25p80@0 { #address-cells = <1>; #size-cells = <1>; compatible = "en25q64"; reg = <0 0>; linux,modalias = "m25p80", "en25q64"; spi-max-frequency = <10000000>; partition@0 { label = "u-boot"; reg = <0x0 0x30000>; read-only; }; partition@30000 { label = "u-boot-env"; reg = <0x30000 0x10000>; read-only; }; factory: partition@40000 { label = "factory"; reg = <0x40000 0x10000>; read-only; }; partition@50000 { label = "firmware"; reg = <0x50000 0x1fb0000>; }; }; }; uart@500 { status = "okay"; }; }; pinctrl { state_default: pinctrl0 { gpio { ralink,group = "i2c"; ralink,function = "gpio"; }; uartf_gpio { ralink,group = "uartf"; ralink,function = "gpio uartf"; }; }; }; ethernet@10100000 { status = "okay"; mtd-mac-address = <&factory 0x4>; pinctrl-names = "default"; pinctrl-0 = <&rgmii1_pins &rgmii2_pins &mdio_pins>; ralink,port-map = "llllw"; // port@4 { // status = "okay"; // phy-mode = "rgmii"; // phy-handle = <&phy4>; // }; // port@5 { // status = "okay"; // phy-mode = "rgmii"; // phy-handle = <&phy5>; // }; // mdio-bus { // status = "okay"; // // phy4: ethernet-phy@4 { // reg = <4>; // phy-mode = "rgmii"; // }; // // phy5: ethernet-phy@5 { // reg = <5>; // phy-mode = "rgmii"; // }; // }; }; wmac@10180000 { ralink,mtd-eeprom = <&factory 0>; }; gsw@10110000 { ralink,port4 = "gmac"; }; sdhci@10130000 { status = "okay"; }; pcie@10140000 { status = "okay"; }; gpio-keys-polled { compatible = "gpio-keys"; #address-cells = <1>; #size-cells = <0>; poll-interval = <20>; s2 { label = "S2"; gpios = <&gpio0 1 1>; linux,code = <0x100>; }; s3 { label = "S3"; gpios = <&gpio0 2 1>; linux,code = <0x101>; }; }; ehci@101c0000 { status = "okay"; }; ohci@101c1000 { status = "okay"; }; };