Bug#451760: linux-image-2.6.22-3-amd64: ps2 keyboard plugged into usb adaptor does not work after reconnecting
On Sun, Nov 18, 2007 at 08:56:03PM +1100, Tim Connors wrote:
> Package: linux-image-2.6.22-3-amd64
> Version: 2.6.22-6
> Severity: normal
>
> If I boot up my laptop with a PS2 keyboard plugged into a USB->PS/2
> mouse+keyboard adaptor, then I have a working keyboard and mouse.
>
> I think it is these lines that correspond to that upon bootup:
>
> usb 3-2: new low speed USB device using uhci_hcd and address 2
> usb 3-2: configuration #1 chosen from 1 choice
> usbcore: registered new interface driver hiddev
> input: Generic USB K/B as /class/input/input1
> 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/input2
> input: USB HID v1.10 Mouse [Generic USB K/B] on usb-0000:00:1d.0-2
>
> If I unplug either end of the adaptor (remove the USB plug, or remove
> the keyboard and mouse from the adaptor), then I only get the mouse
> back. The keyboard flashes its LEDs indicating it has power, but no
> keystrokes get through.
>
> 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.
Cheers,
Moritz
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