Bug#451760: linux-image-2.6.22-3-amd64: ps2 keyboard plugged into usb adaptor does not work after reconnecting
On Fri, 26 Dec 2008, Moritz Muehlenhoff wrote:
> On Sun, Nov 18, 2007 at 08:56:03PM +1100, Tim Connors wrote:
> > dmesg still shows it is still recognising that the adaptor has a
> > keyboard and mouse capability:
> >
> > usb 3-2: USB disconnect, address 3
> > usb 3-2: new low speed USB device using uhci_hcd and address 4
> > usb 3-2: configuration #1 chosen from 1 choice
> > input: Generic USB K/B as /class/input/input13
> > input: USB HID v1.10 Keyboard [Generic USB K/B] on usb-0000:00:1d.0-2
> > input: Generic USB K/B as /class/input/input14
> > input: USB HID v1.10 Mouse [Generic USB K/B] on usb-0000:00:1d.0-2
> >
> > /dev/input/by-id/usb-13ba_Generic_USB_K.B-*mouse show activity when
> > the mouse is moved, but usb-13ba_Generic_USB_K.B-event-kbd doesn't
> > show any activity when the keyboard is used.
> >
> > This is all both from the console and in X. If I plug in a real USB
> > keyboard, it works. Yes, I have tried multiple PS/2 keyboards.
> >
> > I have tried rmmodding all usb related stuff I can find --
> > hid usbhid uhci_hcd and modprobing it and usbkbd to no avail.
>
> This is caused by design limitations of the PS/2 port, so it's not
> surprising that it fails when using PS/2 with a USB adaptor. According
> to http://en.wikipedia.org/wiki/PS/2_connector:
>
> | PS/2 ports are designed to connect the digital I/O lines of the microcontroller
> | in the external device directly to the digital lines of the microcontroller on
> | the motherboard. They are not designed to be hot swappable. Hot swapping PS/2
> | devices usually does not cause damage due to the fact that more modern
> | microcontrollers tend to have more robust I/O lines built into them which are
> | harder to damage; however, hot swapping can still potentially cause damage on
> | older machines, or machines with less robust port implementations.
>
> | If they are hotswapped, the devices must be similar enough that the driver
> | running on the host system recognizes, and can be used with the new device.
> | Otherwise, the new device will not function properly. While this is seldom
> | an issue with standard keyboard devices, the host system rarely recognizes
> | the new device attached to the PS/2 mouse port. In practice most keyboards
> | can be hotswapped but this should be avoided.
However, I'm guessing a PS2-USB adaptor was probably designed so that it
could be plugged into the keyboard, then plugged into the usb port
providing power to the keyboard and host adaptor within the PS2-USB
adaptor, and bringing it all up safely.
Of course, I have no way of proving whether it's the PS2-USB adaptor at
fault here in not transmitting the keyboard codes onto the USB bus, or
whether the kernel's USB interface isn't getting the codes sent to it.
--
TimC
The sooner you fall behind, the more time you'll have to catch up
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