Thinkpad T450s Multi-touch Fails After Suspend

Mint has been my daily driver for a few months now on my laptop, and after the tweaks in the previous post, has been a great experience, except for one thing. The trackpad. The trackpad itself is quite usable, and supports multi-touch gestures. It’s after a suspend that a problem arises.

My most used gesture is the two-finger scroll, as you might imagine. After a suspend, however, this gesture breaks. At first, I thought all multi-touch simply failed. It wasn’t until I got lazy — well, lazier than normal — that my two-finger scroll melted into an all-finger drag. The web page scrolled! Something was up. I played with the trackpad until I boiled it down to the fact that the trackpad decided that two wasn’t enough for a scroll. The new toll is three. Maybe, I thought, I could live with that. It is only one finger, after all. Using it in this state for a day led me to notice that gesture input lag got much longer. Scrolling began to break my immersion, and with it, my concentration. This bug had to be fixed, if only with a hack!

It turns out that this was a bug in the kernel and should be fixed by now in some distributions! Just run updates. I used the Linux Kernel menu in Update Manager and upgraded to kernel version 4.18.0-16, and the two-finger issue seems to be fixed, but the lag seems to still be there, so in a less noticeable way, the fix detailed below is still necessary.

So, let’s get to it. The quick, temporary fix is done by running the two commands below. The first command unloads the module for the trackpad, and the second reloads it. This will tell you whether or not you should continue with the permanent fix.

sudo modprobe -r psmouse
sudo modprobe psmouse

Test out your trackpad and verify it’s working as you’d expect. If it is, keep going!

For the permanent fix, you’ll need to edit your grub configuration. Do that by editing the following file. You can swap nano with a text editor of your choice.

sudo nano /etc/default/grub

Change the following line within from:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

To:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash psmouse.synaptics_intertouch=0"

Then, update grub with:

sudo update-grub

Reboot, and the fix is in. Close the lid to suspend, open it back up and test!

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