I'm trying to get an all-in-one touchscreen PC working as a kiosk (no mouse or keyboard), using the new Ubuntu 11.10, and am almost there.
The touch screen works perfectly if there had been a USB mouse or keyboard attached at boot time.
If I boot without mouse or keyboard, the touchscreen responds randomly - clicking in one place will make the pointer appear somewhere else. Tap the same spot a few times and the pointer will appear in a different place every time.
More info: if you boot with a mouse and then unplug it later, the touchscreen continues to work. If you boot without and plug one in later, it does not help. Restarting the lightdm service (am I right that this is the replacement for gdm?) has no effect either.
In other words, whatever the difference is, it apparently happens at boot time, and as far as I can tell it can only be fixed with a reboot.
Any idea where to start troubleshooting? I did try comparing lsmod output when it's happy vs. unhappy, and it has the same modules.
It did occur to me that it might be a lower-level quirk, like maybe USB support didn't get turned on in BIOS unless there was a device attached at boot; but as it turns out, you can plug in a mouse later and that mouse WILL work, although the touchscreen won't. I think that eliminates the BIOS as a suspect.
The hardware is a Shuttle x50v2 running a 1.8GHz Atom processor, AMI BIOS 1.03.
The touchscreen appears in lsusb this way:
Bus 005 Device 002: ID 0eef:0001 D-WAV Scientific Co., Ltd eGalax TouchScreen