I've now received bug reports from three different people with three
different android-based touchscreen devices. Many people are interested
in running Ubuntu on these devices, and they attempt to use the android
kernel drivers for the touchscreens. Once you peek under the covers,
however, it's obvious that these drivers were written only to the
android specs, which are a subset of what X needs.
I've been working on a kernel document that will hopefully land upstream
soon to outline the input subsystem evdev protocol. It provides
documentation on evdev types and codes, and it gives guidelines on how
drivers should operate.
Since it's not upstream yet and I've been getting a bunch of bug reports
about bad touchscreen behavior, I wanted to point people to the current
patch as I sent it to the linux-input mailing list: