Comment 4 for bug 2004531

A few things:

1. The linux-firmware thing might be a red herring; I downgraded the package to the old version (20220329.git681281e4-0ubuntu3.9) and restarted (choosing kernel version 5.15.0-57-generic), and the problem persisted.

2. I noticed that, even when the touchpad wasn’t working, it could still be found using “xinput list” (listed as “SynPS/2 Synaptics TouchPad”) and tested using “sudo evtest”. (Remember, I made sure that the touchpad wasn’t disabled, either by the hardware switch or in “Mouse Preferences.”) This made me wonder if this all was a kernel bug at all (but that was still my best guess, given that previously my touchpad worked under 5.15.0-57-generic but not 5.15.0-58-generic).

3. Finally, I found a fix for my use-case: https://askubuntu.com/questions/815569/ubuntu-16-04-touchpad-stops-working-after-login/1338177#1338177 I tried using “xinput --list-props 'SynPS/2 Synaptics TouchPad'”, and indeed, one of the results displayed was “Synaptics Off (295): 1”. By using “xinput --set-prop 'SynPS/2 Synaptics TouchPad' 'Synaptics Off' 0”, I was able to get the touchpad working again instantly. Just to make sure, I updated linux-firmware to the latest version (20220329.git681281e4-0ubuntu3.10) and restarted into the latest kernel (5.15.0-60-generic), and once again, the touchpad stopped working after login; but once again, I was able to use “xinput --set-prop 'SynPS/2 Synaptics TouchPad' 'Synaptics Off' 0” in the terminal to restore touchpad functionality. (I’ll put that line in my .profile, so that hopefully I won’t have to do it manually again.)

So I guess this bug report is now a matter of what disabled the touchpad in the first place using that obscure flag. Hmmmm…