[U-Boot] Multiple USB controller support under Uboot

[mike zheng]

Hello,

I am using ISP156x USB PCI controller with Uboot.  Right now, the code
can find only 1 root hub when I use "usb inf" or "usb tree" command to
check the USB tree. If I list the PCI device, it shows there are 2
OHCI and 1 EHCI host controller. Anyone knows why I have only one root
hub? What shall the USB tree looks like for ISP156x USB PCI host
controller?
Thanks,

Mike