[coreboot] USB HUB depth
nico.huber at secunet.com
Thu Mar 9 14:16:50 CET 2017
On 09.03.2017 11:18, Joshua Pincus wrote:
> 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.
are you talking about libpayload's USB stack? coreboot itself doesn't
> 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?
If you are talking about libpayload, there shouldn't be an artificial
limit. Responsible for hub class USB devices is the code in drivers/usb/
generic_hub.c + drivers/usb/usbhub.c.
Hope that helps,
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