hi, Kevin,
I am debugging the coreboot on AMD board.

I found if a device is populated on USB 3.0 port during system power up, the USB3.0 function fail after OS boot up.
If a USB 2.0 device is plugged, the port is OK.
Can you take a look at this?

Here is the debug message.
------------
SeaBIOS (version rel-1.8.0-26-g92f9b91-dirty-20150805_022528-supersrv)
XHCI init on dev 00:10.0: regs @ 0xf0b8a000, 8 ports, 32 slots, 32 byte contexts
XHCI    extcap 0x1 @ f0b8a500
XHCI    protocol USB  3.00, 4 ports (offset 1), def 0
XHCI    protocol USB  2.00, 4 ports (offset 5), def 18
XHCI    extcap 0xa @ f0b8a540
configure_xhci: resetting
configure_xhci: setup 8 scratch pad buffers
xhci_hub_reset port #5: 0x000202e1, powered, pls 7, speed 0 [ - ]
XHCI port #5: 0x00200e03, powered, enabled, pls 0, speed 3 [High]
xhci_alloc_pipe: usbdev 0xbff52960, ring 0xbff9e900, slotid 0, epid 1
xhci_cmd_enable_slot:
xhci_trb_queue: ring 0xbff9ed00 [nidx 1, len 0]
xhci_process_events: status change port #5
xhci_process_events: status change port #1
xhci_process_events: status change port #5
xhci_process_events: ring 0xbff9ed00 [trb 0xbff9ed00, evt 0xbff9ee00, type 33, eidx 1, cc 1]
xhci_alloc_pipe: enable slot: got slotid 1
xhci_cmd_address_device: slotid 1
xhci_trb_queue: ring 0xbff9ed00 [nidx 2, len 0]
WARNING - Timeout at xhci_event_wait:692!
xhci_alloc_pipe: address device: failed (cc -1)
XHCI no devices found
WARNING - Timeout at wait_bit:310!

Joe