Comment 24 for bug 512192

You're correct, the first two bits of the first byte indeed indicates the number of fingers used currently, just like with any other version of the firmware using 6 byte packets. The x- and y-coordinates are also identical to what earlier firmware versions provided, with one minor difference: the high bits of the the bytes representing the upper half of the coordinates apparently have been reused for something else. That's alright, as they've always been zero in earlier firmware versions, and would only be needed for the coordinates if it wanted to report positions outside of the actual dimensions of the pad, which of course it doesn't.

However, the elantech extension of the psmouse module used all the bits available, and therefore relied on them being 0, breaking with new touchpad firmwares.

I've fixed that and sent off the patches to the linux-input mailinglist. See http://www.spinics.net/lists/linux-input/msg08277.html

With all those patches applied, things Just Work on the ASUS UL30A. However, I pretty much hardcoded the firmware version of the touchpad I have. I'm sure there are other versions out there, which would work as well, but I wanted to avoid wrongly identifying non-elantech devices. Therefore I added the force_elantech parameter to the psmouse module. If, with those patches, your elantech touchpad still isn't recognized as such, please retry with force_elantech=1 and report the firmware version as shown in the kernel log.