Created attachment 296359 [details] Contents of /proc/bus/input/devices I've been using Ubuntu 20.04 with the 5.8,0 kernel on a Dell XPS 15 9550. The laptop's touchpad had a hardware defect common to the model (nicknamed "wobble") so Dell sent a tech to replace it. The new touchpad looks identical to the original but the kernel doesn't correctly detect it. The device does work, but appears to the kernel as a "PS/2 Logitech Wheel Mouse," which prevents the use of features like two-finger scrolling, disabling tap to click, and palm detection. A good summary of my troubleshooting steps are here: https://askubuntu.com/questions/1330555/touchpad-detected-as-ps-2-logitech-wheel-mouse-dell-xps-15-ubuntu-20-04 Importantly, I've tried a mainline kernel (5.11.12 and a 5.12.0 release candidate, whereas the current version for the distro is a 5.8.0). I've also tried two bootable USB drives containing Ubuntu 20.04 and 21.04 (release candidate). Nothing has changed the device detection or behavior. The issue is identical in the default Ubuntu desktop and in Plasma. There are no touchpad settings in the UEFI BIOS. I will attached the output of /proc/bus/input/devices, Xorg.0.log, and the `xinput --list` command. Please let me know if there is any other debugging that would be useful. My suspicion is that Dell has ordered a brand new touchpad model for which there is no kernel driver; looking at the logs, the previous model was an elantech, but I'm not sure if the new one is as well.
Created attachment 296361 [details] Output of command `xinput --list`
Created attachment 296363 [details] /var/log/Xorg.0.log
Yesterday I confirmed this was a (second) hardware problem. After I teseted this on Windows 10 and found that OS detected the hardware in exactly the same way (generic PS/2 mouse, plus an I2C_HID device driver that failed to load), and this caused the same behavior. Dell agreed and replaced my laptop's touchpad a second time. After deleting the device in Windows 10 and refreshing, the OS detected the new touchpad fine, so I reinstalled Ubuntu and it's also working fine, with scrolling etc. functioning as normal. So basically, Dell gave me a laptop with a "broken hardware" touchpad and improbably replaced it with a "bad firmware" touchpad that looked like a kernel bug, but wasn't.