I've tried adding basic DT2W feature. It worked as expected for several minutes and then the touch panel start to malfunction (some point is constantly detected as "touched", and thus the system won't respond to any other touch).
Kernel source is here: https://github.com/updateing/android...0/commits/dt2w
(I don't know how to use git then so there's squashed commit for new touch driver and DT2W support)
The driver is taken from Xperia Z kernel source (latest at commit time) and DT2W code from XDA (can't remember
It should be initially for HTC Sensation).
And as for the digitalizer firmware, I don't think Sony will provide us with updates for these things... Firmwares in stock 4.1 and 4.3 are the same.
Finally, the digitalizer on Xperia TX may be Synaptics S3000, instead of S3200. I checked this by adding a pr_info in init function of driver (half a year ago). Don't know if the other two phones are using the same..