I had the same problem (keyboard not working, touchpad working) for a 6.x kernel. The workaround from Johannes and Bernd worked for me, though I only used "quiet splash i8042.nomux=1" and did not test the additional "i8042.reset".
System: Fujitsu Lifebook 7U15A1, Ubuntu 22.04.3 LTS, Kernel 6.2.0-36-generic x86_64
Btw: "cat /sys/class/dmi/id/chassis_type" still shows "10" and the Fujitsu 7U15A1 is not a tablet nor a convertible.
I had the same problem (keyboard not working, touchpad working) for a 6.x kernel. The workaround from Johannes and Bernd worked for me, though I only used "quiet splash i8042.nomux=1" and did not test the additional "i8042.reset".
System: Fujitsu Lifebook 7U15A1, Ubuntu 22.04.3 LTS, Kernel 6.2.0-36-generic x86_64
Btw: "cat /sys/class/ dmi/id/ chassis_ type" still shows "10" and the Fujitsu 7U15A1 is not a tablet nor a convertible.