Touchpad differences between launching GNOME in lxdm vs gdm3

[Pinguinsan]

I have a Chromebook Pixel (2015) running GalliumOS 3.0. When I launch GNOME (3.28.3) via lxdm (the default display manager for GalliumOS), the touchpad works well. The launch command for gnome is in lxdm.conf (session=/usr/bin/gnome-session). However, when I launch gnome via gdm3 (GNOME on Xorg), the touchpad has a completely different acceleration curve and sensitivity. Any ideas for how I could track down these differences? As far as I can tell, both are using libinput and Xorg (NOT Wayland).

On both, xinput list-devices yields:

⎡ Virtual core pointer id=2 [master pointer (3)]

⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]

⎜ ↳ Atmel maXTouch Touchpad id=9 [slave pointer (2)]

⎜ ↳ Atmel maXTouch Touchscreen id=10 [slave pointer (2)]

⎣ Virtual core keyboard id=3 [master keyboard (2)]

↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]

↳ Power Button id=6 [slave keyboard (3)]

↳ Video Bus id=7 [slave keyboard (3)]

↳ NCM-G102: NCM-G102 id=8 [slave keyboard (3)]

↳ AT Translated Set 2 keyboard id=11 [slave keyboard (3)]

and the output of xinput list-props 9 is identical under both. Any ideas?

[Sauron]

It could have something to do with dconf. Check if you see something that could affect your touchpad in

/usr/share/gdm/greeter-dconf-defaults

or in

/etc/dconf/db/gdm.d

 

You can also try to tweak the settings to suit you manually from within Gnome.