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SubjectRe: PROBLEM: PS/2 keyboard does not work with 2.6.15
On 1/9/06, Alan Stern <> wrote:
> On Mon, 9 Jan 2006, Dmitry Torokhov wrote:
> > > It would be nice to know which part of the usb-handoff code causes the
> > > problem.
> >
> > Well, it's not handoff code causing problems per se, it's just that it
> > does not look like it performs handoff. If it did then disabling USB
> > legacy emulation in BIOS would have no effect, right?
> On the other hand, if the BIOS worked correctly then the ps/2 port would
> have no problems regardless of whether USB legacy emulation was on or off.
> Given that the keyboard works during bootup, I see only two possibilities:
> The USB handoff code somehow causes the BIOS to mess up the
> state of the 8042;
> The 8042 driver interacts badly with the firmware when USB
> legacy emulation is on, and the USB handoff code doesn't
> successfully turn off legacy emulation.
> My earlier suggestion was an attempt to test the first possibility. The
> second is harder to test because it implies problems in both the 8042
> driver and the USB handoff code.

My experience is that USB legacy emulation in BIOS + ACPI works as
long as you do not touch it and gets terribly confused if someone
tries to actually use i8042 (like enable active multiplexing mode with
4 AUX ports). As soon as BIOS takes its dirty hands off i8042
everything works fine.

The problem it seems that when usb-handoff code was moved from pci
quirks and enabled inconditionally something happened so it stopped
doing handoff.

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