前几天我更新到了 16.04，我的启动时间变得非常慢。我在 Macbook Pro 上使用重新索引。从 dmesg 输出来看，我认为这是 xhci_hcd 驱动程序的问题。我见过几个地方有人遇到同样的问题，但我还没有找到解决办法。
以下是一些相关信息：
➜ ~ lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/11p, 480M
|__ Port 1: Dev 6, If 0, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 1: Dev 6, If 1, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 1: Dev 6, If 2, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 2: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
|__ Port 2: Dev 2, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
|__ Port 3: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 3: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 3: Dev 4, If 2, Class=Vendor Specific Class, Driver=btusb, 12M
|__ Port 3: Dev 4, If 3, Class=Wireless, Driver=btusb, 12M
|__ Port 3: Dev 4, If 4, Class=Vendor Specific Class, Driver=btusb, 12M
|__ Port 3: Dev 4, If 5, Class=Application Specific Interface, Driver=, 12M
|__ Port 5: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 5: Dev 5, If 1, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 5: Dev 5, If 2, Class=Human Interface Device, Driver=bcm5974, 12M
|__ Port 5: Dev 5, If 3, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 5: Dev 5, If 4, Class=Human Interface Device, Driver=usbhid, 12M
相关 dmesg 部分：
............
[ 6.651769] usb 1-3: new full-speed USB device number 3 using xhci_hcd
[ 11.664027] xhci_hcd 0000:00:14.0: Command completion event does not match command
[ 11.664030] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 11.868052] usb 2-3: device not accepting address 2, error -62
[ 16.672349] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 16.672377] usb 1-3: hub failed to enable device, error -62
......
[ 22.464663] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 27.680953] xhci_hcd 0000:00:14.0: Command completion event does not match command
[ 27.680956] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 27.884988] usb 2-3: device not accepting address 3, error -62
[ 38.481586] xhci_hcd 0000:00:14.0: Command completion event does not match command
[ 38.481590] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 43.697916] xhci_hcd 0000:00:14.0: Timeout while waiting for setup device command
[ 43.901909] usb 2-3: device not accepting address 4, error -62
.........
和内核版本
➜ ~ uname -r
4.4.0-22-generic