Tuesday, August 26, 2008

Wacom USB TabletPCs: persistent by-id links

Since the linuxwacom package supports TabletPCs with USB tablets we have the problem to find the correct devices under /dev/input/* for the xorg.conf settings. While the input device of the stylus was easy to find (/dev/input/by-id/usb-Tablet_ISD-V4-event-mouse) but strange named, the input device file for the touch device needed to be searched by the user since there was no persistent link under /dev/input/by-id/ that would allow to use the same link for all USB based Wacom TabletPCs.

Now I've found a way to change udev to set also a persistent by-id link for the touch device. I also change the naming of the link to the stylus device. With my patch you get now these links under /dev/input/by-id/ :
tux@linux:/ # ls /dev/input/by-id/
The input devices you needed for you xorg.conf are the *-event-* links.

If you use openSUSE you can get patched udev versions from my buildservice repo. I've patched also SaX2 to handle the new link names (packages see here). Note: you need SaX2/udev to get everything working correctly and you may need to run SaX2 to update your actual X configuration.