SUMMARY After updating my neon installation to plasma 5.17.4 with kernel 4.15.0-72, the touchpad stopped working completely. The synaptics touchpad is still recognized as an input device in `xinput`, but it does not send any X event. If I boot with the previous kernel, 4.15.0-70, the boot screen shows neon 5.17.3, and everything works perfectly. I'm not sure if it is a kernel bug, an Ubuntu bug, or a Neon bug. My laptop is a Dell XPS 13 9333. STEPS TO REPRODUCE 1. Boot KDE Neon 2. 3. OBSERVED RESULT The touchpad does not work at all. No motion, no click, no scrolling. EXPECTED RESULT The touchpad should work as always. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.17.4 KDE Frameworks Version: 5.64 Qt Version: 5.13.2 ADDITIONAL INFORMATION Behavior observed in a Dell XPS 13 9333 machine.
Apparently the bug affects any ubuntu 18.04 installation, so it's not directly related to neon or KDE: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854895
Thanks for the update. Users there confirmed it is a kernel regression; changing status.