[coreboot] USB Support on Apollo Lake

Gailu Singh gailu96 at gmail.com
Mon Mar 20 13:01:55 CET 2017

Hi Werner,

Thanks for your detailed clarification. Looks like Intel removing various
legacy interfaces and support for alternatives is yet to be developed in
grub. No only they removed USB2.0 altogether, they also removed IO mapped
UART and we can't get serial console working on this board either with grub.

For USB I am making a last attempt to use PCIE USB2.0 card and ordered
following from Aliexpress but I have serious doubts if this will work in
Grub2. Will post the results once I get the cards delivered.


Thank you very much once again.

On Mon, Mar 20, 2017 at 5:18 PM, Zeh, Werner <werner.zeh at siemens.com> wrote:

> Hi Gailu.
> I don't think that one can configure the xHCI to behave like an EHCI so
> that GRUB2 can natively support it.
> xHCI has different version number in the PCI space which will prevent the
> EHCI driver in GRUB2 to use this controller at all.
> Not speaking about the complete different register set and operational
> model.
> What in turn should work is that "some of the BIOS" (which in
> coreboot-context is the payload like SeaBIOS) will handle all the
> xHCI stuff and provide a legacy interface to the OS (and here GRUB acts as
> an OS) to just read mass storage devices using interrupts.
> Beside that you are lost with GRUB2 and xHCI, sorry!
> Werner
> >Hi Experts,
> >
> >Does coreboot support USB port initialization in legacy mode on Apollo
> Lake as some of the BIOS does so that grub or other payloads can use it as
> USB2.0?
> >
> >There is no USB2.0 port on this board and Grub2 doesn't support xhci so
> we seems to be reaching to a dead end.
> >
> >I am trying to see if the dual role USB ports can be initialized in
> coreboot/fsp so that they can act as USB2.0 for payloads.
> >
> >Thanks
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