OLPC trac 4501 - If USB enumeration of a device fails, ("Failed to set device address: N"), retry the reset-port / set-address sequence with a 5-second delay in between. This has proven to be effective with a problem USB disk that used to consistently fail to work with OFW. This fix does not affect startup time in the usual case of quick-response devices.
cpu/x86/pc/olpc/suspend.fth
dev/usb2/hcd/ehci/probe.fth