linux-kernel - Re: Wonkiness with keyboard adapter - not sure if it's in USB or input systems

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Date:	Tue, 26 Apr 2011 20:17:51 -0400
From:	Valdis.Kletnieks@...edu
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-input@...r.kernel.org
Subject: Re: Wonkiness with keyboard adapter - not sure if it's in USB or input systems

On Tue, 26 Apr 2011 23:29:42 +0200, Jiri Kosina said:
> On Tue, 26 Apr 2011, Valdis.Kletnieks@...edu wrote:
>
> > > > Bus 001 Device 006: ID 0e8f:0020 GreenAsia Inc. USB to PS/2 Adapter
> >
> > > Have you tried testing the adapter by plugging it in after the system
> > > is running?
> >
> > It works fine at the Grub screen.
> >
> > It *doesn't* work for the kernel when it initially starts up, even though a few
> > seconds ago the hardware worked just fine.
> >
> > It *does* work after I've unplugged/replugged it - I've tested both the USB
> > side and the PS2 side, in either case it starts working.

> It seems like the BIOS handover of the USB input device doesn't work
> properly.
>
> The way things usually work in such situations -- BIOS is able to
> understand USB input devices in a very basic mode (hidp) and translate the
> events into PS/2-looking events, so that things like grub (which don't
> understand USB HID) are able to see keyboard events -- BIOS presents those
> as PS/2 devices.
>
> Once kernel is booted, it takes over devices in this 'legacy' mode from
> BIOS, and initializes them properly as USB input devices.
>
> Seems like this process is broken on your system. Could you please try to
> disable legacy USB emulation in your BIOS, and see if the problem
> persists? (it will make USB keyboard unavailable in grub).

Possible datapoint - the USB handoff can't be *totally* broken on the laptop,
because it handled another Microsoft Natural keyboard with a USB on it just
fine, so it's something specific to the GreenAsia adapter.

I disabled legacy USB emulation, and as expected, the keyboard wasn't available
to grub.  It was *also* unavailable to the initrd until I did the 'disc/reconnect' thing,
at which point it started working.  (Sorry, don't have the dmesg from that
one, can get it tomorrow (Wed) morning if you want.  And any advice on
additional debugging I can turn on to help would be accepted too).



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