基于3.14.28的bsp、2014.04的uboot、imx6q。dmesg | grep -i usb的信息如下：
root@~# dmesg | grep -i usb
[ 0.000000] Linux version 3.14.28 (wucheng@sam-H57M-USB3) (gcc version 4.9.1 (GCC) ) #17 SMP PREEMPT Wed Dec 13 09:59:30 HKT 2017
[ 0.264602] usb_otg_vbus: 5000 mV
[ 0.265055] usb_h1_vbus: 5000 mV
[ 0.269031] usbcore: registered new interface driver usbfs
[ 0.269165] usbcore: registered new interface driver hub
[ 0.269351] usbcore: registered new device driver usb
[ 0.269650] usbphy_nop1.11 supply vcc not found, using dummy regulator
[ 0.269871] usbphy_nop2.12 supply vcc not found, using dummy regulator
[ 1.354220] usbcore: registered new interface driver rtl8723bu
[ 1.361290] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 1.370893] usbcore: registered new interface driver cdc_wdm
[ 1.375394] usbcore: registered new interface driver usb-storage
[ 1.381847] 2184800.usbmisc supply vbus-wakeup not found, using dummy regulator
[ 1.395388] 2184200.usb supply vbus not found, using dummy regulator
[ 1.411437] ci_hdrc ci_hdrc.1: new USB bus registered, assigned bus number 1
[ 1.437158] ci_hdrc ci_hdrc.1: USB 2.0 started, EHCI 1.00
[ 1.442759] hub 1-0:1.0: USB hub found
[ 1.559184] usbcore: registered new interface driver bcm203x
[ 1.563689] usbcore: registered new interface driver btusb
[ 1.572490] usbcore: registered new interface driver ath3k
[ 1.767225] usb 1-1: new full-speed USB device number 2 using ci_hdrc
[ 2.007269] usb 1-1: device descriptor read/64, error -71
[ 2.327218] usb 1-1: device descriptor read/64, error -71
[ 2.557200] usb 1-1: new full-speed USB device number 3 using ci_hdrc
[ 2.777189] usb 1-1: device descriptor read/64, error -71
[ 3.347961] usb 1-1: device descriptor read/64, error -71
[ 3.574252] usbcore: registered new interface driver usbhid
[ 3.578684] usb 1-1: new full-speed USB device number 4 using ci_hdrc
[ 3.583890] usbhid: USB HID core driver
[ 3.716096] usb_h1_vbus: disabling
[ 3.718271] usb_otg_vbus: disabling
[ 4.087181] usb 1-1: device not accepting address 4, error -71
[ 4.207227] usb 1-1: new full-speed USB device number 5 using ci_hdrc
[ 4.687184] usb 1-1: device not accepting address 5, error -71
[ 4.691808] hub 1-0:1.0: unable to enumerate USB device on port 1
root@~#
