关于IMX6UL第二个USB接口在linux驱动的问题

[我爱下载]

usb2作为host，其ID已经直接接地，VBUS悬空，设备采用外部供电方式。设备树中加载了usb2的驱动

   usbotg2: usb@02184200 {
    compatible = "fsl,imx6ul-usb", "fsl,imx27-usb";
    reg = <0x02184200 0x200>;
    interrupts = <GIC_SPI 42 IRQ_TYPE_LEVEL_HIGH>;
    clocks = <&clks IMX6UL_CLK_USBOH3>;
    fsl,usbphy = <&usbphy2>;
    fsl,usbmisc = <&usbmisc 1>;
                ahb-burst-config = <0x0>;
                tx-burst-size-dword = <0x10>;
                rx-burst-size-dword = <0x10>;
    status = "disabled";
   };

&usbotg2 {
 pinctrl-names = "default";
 pinctrl-0 = <&pinctrl_usbotg2>;
 dr_mode = "host";
    disable-over-current;
 status = "okay";
};

现在的问题是，系统启动后，在/sys/bus/usb/devices 下只能看到

1-0:1.0@ usb1@

如果给外部设备开机，系统一直在提示下面的信息：

usb 1-1: new high-speed USB device number 119 using ci_hdrc

但是无法识别出设备来，如果usb1接上外部设备了，usb2上就识别出来了，这是怎么回事

[weidong_sun]

Hello JiYong,

    USB VBUS couldn't be floated, it should be supplied 5V power. try it , please!

Have a great day,
TIC   weidong sun

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[我爱下载]

非常感谢您的回复，我测试后发现确实VBUS必须接入确定的高电平。