[coreboot] [GSoC] option rom problems with DBM690T+VT6202L

Stefan Reinauer stepan at coresystems.de
Thu Jul 30 19:15:05 CEST 2009

On 7/29/09 3:58 AM, Peter Stuge wrote:
> Note that it is not in fact a UHCI controller if it supports USB 2.0.
> It is difficult (maybe impossible) to find a UHCI PCI card.
> An EHCI controller will only and always communicate with high-speed
> devices using EHCI.
> The EHCI controller and it's so-called companion controllers do not
> mirror each port. Any connected device will only appear attached to
> one controller, and it will always be the same controller for a given
> device and a given physical port.
> In other words, for you to be able to use UHCI with this PCI card,
> you must attach a USB 1.1-only MSC device to one of the ports.
This is interesting, since we have not seen this problem on any Intel
chipset, which have EHCI controllers but do UHCI, too.
It's never been a problem to use the UHCI stack with USB 2.0 capable
devices. Are they doing something special?
I never saw an EHCI only controller, all of them came with either UHCI


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