A small number of users have experienced sporadic issues with getting the USB port to work.
1.) The error will show up as the following message during boot:
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
ehci-pci: EHCI PCI platform driver
xusbps-dr e0002000.usb: Unable to init USB phy, missing?
2.) The problem is significantly worse on some boards
3.) Once initialized, the USB port works fine.
4.) Similar problems with the Xilinx USB driver has been reported elsewhere:
https://github.com/Xilinx/linux-xlnx/issues/19
Workarounds that have had some success:
1.) Using a longer USB cable
2.) Pressing the reset button after a power cycle to force a reboot.
We are still looking for the root cause of this issue, hopefully we will have a resolution soon.
Andreas