touchpad mouse stutters/stops on slow movement

[Haiko von Holten]

Binary package hint: xserver-xorg-input-synaptics

On slow movement the touchpad/mouse does not move or stutters coarsely.
Definition of slow movement: The fingertip does not move due to stiction and then suddenly starts moving. This stopping and moving is continued by the user. The fingertip is "stuttering" across the touchpad.

Example: The user tries to position the mouse exactly and therefore moves his fingertip very slow. It's very hard to position the mouse because nothing is happening in the first instance. After a while and some distance on the touchpad without effect the mouse jumps for half an inch or so.

If the mouse is moving fast and smoothly everything is alright.

This behaviour appears in version 0.99.3-2ubuntu5 only. In version 0.99.3-2ubuntu4 every movement is somehow interpreted an it is possible to position the mouse exactly by slow movement.

Therefore i suppose it's got something to do with this bug-fix:
* debian/patches/111_fix_jumpy_cursor.patch:
    - Prevent the cursor from jumping when movement
      events are lost or when they take place in
      such a little time that no human hand could
      ever trigger them (LP: #365943).

I hope somebody is looking though this description. :)

[Haiko von Holten (hholten)]

$ lshal | grep -A 5 input.touchpad | grep product
info.product = 'AlpsPS/2 ALPS GlidePoint' (string)

[merc (merc)]

Hi,

I filed a very similar bug report.
Have a look:

https://bugs.launchpad.net/ubuntu/+bug/372090

What's interesting, is that I think the bug was there beforehand, we just never noticed. Are you able to put a live CD for 8.10 there, and CAREFULLY test it?

Bye!

Merc,

[merc (merc)]

Hi,

I offer a $50 bounty to the person who provide a 100% effective patch to get this 100% fixed.

Merc.

[Joost Cassee (jcassee)]

I can confirm this bug on my Dell Inspiron 510m with AlpsPS/2 ALPS GlidePoint touchpad. Downgrading to version 0.99.3-2ubuntu4 fixes the problem. However, the downgrade triggers bug #327428: some pixels can not be reached anymore.

By the way, doing 'rmmod psmouse; modprobe psmouse proto=imps' makes the touchpad even smoother, but of course removes scrolling and such.

[Ian Gough (igough57)]

This problem makes any kind of fine positioning difficult.

>lshal | grep -A 5 input.touchpad | grep product
  info.product = 'AlpsPS/2 ALPS GlidePoint' (string)

If I run
>synclient -m 10

And very very slowly move my finger across the touchpad (about 30-40 seconds to traverse the touchpad), I can see the x value slowly changing from about 80 to 970 but the pointer does not move at all.

[Ian Gough (igough57)]

For those of you that still has this problem, here is a temporary workaround until it gets fixed.

During the process of verifying some code in the synaptic.c that looks questionable, I stumbled upon the fact that if I uninstalled the xserver-xorg-input-synaptics package, my Alps touchpad on my Dell Inspiron 1720 works very smoothly with no stuttering. I can now rock my finger on the touchpad to make tiny adjustments to the cursor position, something that I could not do with the xserver-xorg-input-synaptics package in 9.04. Basic touchpad settings are now configured using the Mouse applet.

[Joost Cassee (jcassee)]

I tried uninstalling (purging) the xserver-xorg-input-synaptics package, but that just made my touchpad inactive...

[merc (merc)]

Hi,

This is probably not good news, but... I uninstalled xserver-xorg-input-synaptics . Things got better... and worse. Things got "better" meaning that now the delay between the finger movement and the actual mouse movement is not as bad. Worse because now the pointer is "stuttery" -- especially when using it for precise movements, it just seems to move around a lot.

Maybe the problem is not Synaptics after all?

Merc.

[selkovjr (selkovjr-observercentral)]

I would like to confirm the bug, and provide additional data.

My definition of "slow": when I move my finger at 1 mm/s the cursor does not move *at all*. Same when I roll the tip of my finger to drive the cursor where I need it to be (that's what I usually do when I need single-pixel precision).

I can watch the events generated by the kernel with synclient, but all of them are ignored by X up to a certain motion speed, beyond which the cursor starts moving, but in jerky sort of way.

For me, this started happening very recently (about 2 days ago), but I was mostly reading during that time and didn't notice a definite event that I could link to the change. If this is indeed caused by xserver-xorg-input-synaptics, I would like to know which was the last working version. I did a lot of precise work in Gimp just last weekend, and did not notice any inconvenience. In between, I have upgraded my nvidia-glx-180 to 185, and that is the only upgrade I am aware of, although I can't see how it would be related to the touchpad problem. Now I am unable to use the touchpad for anything except selecting windows: I can't cut and paste and I can't even reliably put the cursor on the right line in a text editor. At the same time, external mice, pen tablet and the built-in track stick work smoothly.

xserver-xorg-input-synaptics:
  Installed: 0.99.3-2ubuntu5
  Candidate: 0.99.3-2ubuntu5
  Version table:
 *** 0.99.3-2ubuntu5 0
        500 http://ppa.launchpad.net jaunty/main Packages
        100 /var/lib/dpkg/status
     0.99.3-2ubuntu4 0
        500 http://archive.ubuntu.com jaunty/main Packages

"AlpsPS/2 ALPS GlidePoint" id=2 [XExtensionPointer]
        Num_buttons is 12
        Num_axes is 2
        Mode is Relative
        Motion_buffer is 256
        Axis 0 :
                Min_value is 0
                Max_value is 1023
                Resolution is 1
        Axis 1 :
                Min_value is 0
                Max_value is 767
                Resolution is 1

It's on Dell m4300 running Jaunty.

--Gene

[selkovjr (selkovjr-observercentral)]

I am sorry -- I did read the previous posts but overlooked the answer to my question.

Reverting to 0.99.3-2ubuntu4 fixed it, but, as merc mentioned on 2009-05-23, it is probably still broken to a lesser extent. Now I do recall that had I frequent problems landing a pasted selection on a pixel, but I attributed that to my own lack of dexterity. It often worked as I intended, but sometimes I would overshoot by 2-3 pixels and have to go back to find the right position.

Now I repeated the test with synclient after rolling back xserver-xorg-input-synaptics, and I can see that my X still misses some events, although now hitting the correct pixel is at least possible, and correct placement of the insertion point in a text buffer and selecting regions in it are completely trouble-free.

There is roufgly a 10-fold difference in the number of events missed in 0.99.3-2ubuntu4 and 0.99.3-2ubuntu5.

Just a WAG, but could this problem have anything to do with ALPS not being Synaptics? Did anyone notice this with Synaptics?

--Gene

[Alberto Milone (albertomilone)]

Can you still reproduce the problem with the latest version of the driver in Karmic?

[Bryce Harrington (bryce)]

We're closing this bug since it is has been some time with no response from the original reporter. However, if the issue still exists please feel free to reopen with the requested information. Also, if you could, please test against the latest development version of Ubuntu, since this confirms the bug is one we may be able to pass upstream for help.