Touchpads are unresponsive and laggy for small finger movements

An interesting test is to move your finger around in small circles on the touchpad. If the hysteresis is too high then you will see the cursor move in a more square-like shape.

See also:
https://bugs.freedesktop.org/show_bug.cgi?id=98839
https://bugs.freedesktop.org/show_bug.cgi?id=94986

Hmm, if blacklisting or writing custom configs is the solution then maybe this bug should be hardware-specific.

Status changed to 'Confirmed' because the bug affects multiple users.

test the patch from https://bugs.freedesktop.org/show_bug.cgi?id=99410

Yes it sounds like Peter had already prototyped something like what I later suggested in
https://bugs.freedesktop.org/show_bug.cgi?id=98839#c27

However I already know that's not going to fix this problem. Fixing hysteresis like that only solves the problem of the cursor moving in squares when the finger is moved in circles, at most. Whereas the X1 Carbon gen4/gen5 (and possibly X1 Yoga too) require all hysteresis to be turned _off_. This is because the hardware itself starting in gen4 has so much hysteresis built in (firmware change?) that any additional hysteresis in software makes it unusable. I can move my finger almost a centimeter before the cursor moves...

Workaround:

1. sudo apt install xserver-xorg-input-synaptics
2. Log out
3. On the login screen select session "Ubuntu on Xorg"
4. After logging in, disable hysteresis:
   synclient HorizHysteresis=0 VertHysteresis=0

This won't cure laggy hardware but it will at least eliminate the software lag in touchpad response.

Next, since you're now using Xorg and not Wayland, you likely are also using the Intel graphics driver for Xorg. The intel xorg graphics driver is also laggier than Wayland by default (by one frame or ~16.6ms). You can fix that by creating a /etc/X11/xorg.conf with:

Section "Device"
  Identifier "MyLaptop"
  Driver "intel"
  Option "TripleBuffer" "off"
EndSection

Although this does risk hurting the framerate smoothness of gnome-shell while it is still relatively young and un-optimized, you can choose between smoother graphics ("TripleBuffer" "on") or lower latency ("TripleBuffer" "off").

Don't forget to also 'chmod 644 /etc/X11/xorg.conf' or else logging in may fail.

intel hasn't been the default driver since 16.10, modesetting is (on gen4 and up)

Ah, yes sorry.

I've changed the bug title again because generalizing was just asking for trouble. There would be a never-ending stream of "me too! not fixed!" from other users with other hardware.

Fix not actually committed to anything in Ubuntu yet. Turns out the fix is in master, so that's probably libinput 2.0 and not 1.9 :P

Correction: libinput 1.10 comes after 1.9. Expect the fix in libinput 1.10

Fix for bionic attached.

Although if someone wants to make it a fix for Debian in general then that's fine too.

This bug was fixed in the package libinput - 1.9.4-1

---------------
libinput (1.9.4-1) unstable; urgency=medium

  * New upstream release.
  * Add fix-lp1696929.patch to fix unresponsive/laggy touchpad behaviour
    caused by inappropriate use of software hysteresis (LP: #1696929).
    Thanks, Daniel van Vugt!

 -- Timo Aaltonen <email address hidden> Thu, 14 Dec 2017 12:40:25 +0200

note that this patch does not work properly, it seems to be too aggressive disabling hysteresis so I dropped it from Debian, see https://bugs.debian.org/884599

reopening, as libinput got autosynced

I'll see what upstream has to say about a plan for v1.10 ...

Generalised the bug title again. I now realise other common machines like the Dell XPS 13 and Macbook Air 13 experience this same bug. In all cases I have to revert to a Xorg session and installing xserver-xorg-input-synaptics to be able to use the touchpad adequately.

Timo,

Any chance we could patch this for bionic only? No need to wait for libinput release 1.10. Just take the fixes that are in the master branch already and backport.

That would avoid clashing with James using Debian. Actually in general I think many more people will need the fix than the status quo. It would be very bad if the LTS went out without this fixed. A dramatic step backwards for lots of people. And many of them won't know it's coming until they do their LTS upgrade.

In my mind this libinput fix is more important than just about everything else graphical and interactive because without it, the desktop is just too frustrating to use. And worse, the primary workaround for this bug is to revert to Xorg+synaptics, so we also lose the dream of being able to stay in Wayland.

Actually we may be blocked waiting to see if the first fix for James' issue lands:

https://lists.freedesktop.org/archives/wayland-devel/2018-January/036475.html

We should include that if it does.

The second fix for James' issue we can ignore providing it stays a kernel problem:

https://bugs.freedesktop.org/show_bug.cgi?id=104533

I don't understand how we can ignore a well known regression? If there's a kernel patch as a result then surely we'll want it in bionic?

Actually we don't need to ignore it. We can release the fixes for the regression. The fixes are:

1. libinput: https://lists.freedesktop.org/archives/wayland-devel/2018-January/036475.html (not landed yet)
2. kernel: https://bugs.freedesktop.org/show_bug.cgi?id=104533 (not tested yet)

James will need both, but as I understand it only the libinput fix is required for all touchpads in general. So we only need to wait for #1. I plan on testing it across a few laptops this week to get ahead of the ball.

A fresh fix for bionic, that should satisfy everyone now.

uploaded, stuck in the queue like everything else

This bug was fixed in the package libinput - 1.9.4-2ubuntu1

---------------
libinput (1.9.4-2ubuntu1) bionic; urgency=medium

  * Restore and refresh fix-lp1696929.patch to fix unresponsive/laggy touchpad
    behaviour caused by inappropriate use of software hysteresis (LP: #1696929)
    This time the patch includes the fix for Debian bug #884599.

 -- Daniel van Vugt <email address hidden> Mon, 22 Jan 2018 16:18:09 +0800

Yes, upstream reopened this bug because it regressed. I'm not sure how we want to handle that in Launchpad.

I see a much worse version of this problem on my brand new ThinkPad X1 Carbon 6th gen: the mouse cursor moves/clicks only about 5% of the time I use the touchpad. The Trackpoint doesn't work at all. Installing Ubuntu was a keyboard-only affair, and I hoped that some updates would fix this dealbreaker issue. In Ubuntu Budgie 18.04, the mouse worked fine after the DE started up, but was frozen during the startup for ~30 seconds. So this isn't a hardware problem.

I've already installed xserver-xorg-input-synaptics and rebooted - no luck.

What else can I try? The mouse responds normally but only ~5% of the time I use the touchpad (move cursor, or tap/click).

Actually my issue is much closer to bug 1791427 (comment #62).

Regardless, this bug is closed. If you have any new problems with xserver-xorg-input-synaptics installed then please open a new bug by running:

  ubuntu-bug xserver-xorg-input-synaptics

Otherwise please run:

  ubuntu-bug libinput