[coreboot] USB problem with Haswell+LynxPointLP motherboards

Trammell Hudson hudson at trmm.net
Tue Oct 10 15:44:28 CEST 2017

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



More information about the coreboot mailing list