Comment 21 for bug 1265885

Kent Baxley's analysis in comment #18 is correct. Some (but not all) models of Dell XPS13 contain the Synaptics touchpad affected by this problem.

Until a newer Synaptics i2c driver becomes available, the recommended solution for Ubuntu 14.04 (Trusty) is to blacklist the i2c_hid driver, which will return the Synaptics touchpad to full functionality.

To test whether this workaround will affect you, run the 'xinput' command. If the output contains a "DLL060A:00 ..." line (indicating that it has been detected by the i2c_hid driver), then you may need this workaround.

To apply the workaround, run the following command:

    $ echo "blacklist i2c_hid" | sudo tee -a /etc/modprobe.d/blacklist.conf

... and then reboot your system. The 'xinput' command should now show a "SynPS/2" line instead of the "DLL060A:00" line, and full touchpad functionality should be restored.