[coreboot] USB problem with Haswell+LynxPointLP motherboards

Zoran Stojsavljevic zoran.stojsavljevic at gmail.com
Tue Oct 10 18:59:28 CEST 2017

> I'm going to try the hack to disable xhci, as suggested by Zoran and
Аладышев's earlier email.

You might try both variants. Do not forget, both ehci and xhci hubs are on
different clocking domains, so you can set only one at the time (no
workaround/circumventing tricks).

I would advise to try only with xhci first. And use only USBs 2.0. Should
work. Then you can also try vice versa.


On Tue, Oct 10, 2017 at 3:44 PM, Trammell Hudson <hudson at trmm.net> wrote:

> On Mon, Oct 09, 2017 at 07:55:34PM -0700, Julius Werner wrote:
> > My gut feeling would be to blame ACPI. The Linux patch is about
> > caching a host controller register in the kernel, and in some cases
> > (e.g. ehci_reset()), the patch re-reads the cached version from the
> > hardware whereas the previous code didn't.
> Even with reversing the patch (modifying the ehci code to always
> read from the command register), my Haswell board still won't
> enumerate the USB devices.  I'm going to try the hack to disable
> xhci, as suggested by Zoran and Аладышев's earlier email.
> Likely unrelated, I'm also having a problem enabling ACPI from the Linux
> kernel, although most everything else seems to work with interrupts
> and PCIe, so for the time being I have a hack in acpi_enable to pretend
> things worked.
> [    0.017031] ACPI: Core revision 20160831
> [    0.264132] ACPI: 4 ACPI AML tables successfully acquired and loaded
> [    0.271241] ACPI: setting ELCR to 0200 (from 0a00)
> [    0.376881] ACPI Error: Hardware did not enter ACPI mode
> (20160831/evxfevnt-113)
> [    0.385158] acpi_enable:114 faking ACPI mode
> https://github.com/osresearch/heads/issues/260
> https://github.com/osresearch/heads/issues/248
> --
> Trammell
> --
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