[coreboot] USB HUB depth

[Joshua Pincus]

Hi,

I'm new to coreboot and to this group.  As this is my first post, let me
thank you folks for developing an impressive and incredibly useful product!

I recently fired up the coreboot USB stack on an x86 development board.
The USB stack reported back that I have 2 EHCI host controllers on the
board.  Each controller, in turn, has a number of ports.  Attached to at
most 1 of the ports beyond each controller is a USB 2.0 hub.  Each hub, in
turn, has a number of ports which the coreboot USB stack enables.

My issue is this: I see the host controllers get initialized.  I see the
aforementioned hubs get initialized.  I see the ports underneath those hubs
get enabled.  I do not see nor can I find any existing code that scans and
attaches the ports associated with those hubs.  Consequently, none of the
devices (aka keyboard, USB stick, etc.) plugged into the ports beyond those
hubs are scanned and attached.  Put another way, it looks like the USB
stack, as currently written, only scans and attaches devices at tier 0 and
tier 1.  Anything beyond the hub is merely enabled.

Am I wrong or missing something?  How difficult would it be to continue the
process of recursion to subsequent tiers?

Thanks,
JP
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