Bug 665413 - Trackpad jitter
Summary: Trackpad jitter
Keywords:
Status: CLOSED UPSTREAM
Alias: None
Product: Fedora
Classification: Fedora
Component: xorg-x11-drv-synaptics
Version: rawhide
Hardware: i586
OS: Linux
low
medium
Target Milestone: ---
Assignee: Peter Hutterer
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2010-12-23 16:23 UTC by Richard Burton
Modified: 2011-01-03 21:49 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Fedora 14 -Gnome updated
Last Closed: 2010-12-24 19:32:43 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
FreeDesktop.org 32642 0 None None None Never

Description Richard Burton 2010-12-23 16:23:36 UTC
Description of problem:
Cursor location jitters with finger on track-pad

Version-Release number of selected component (if applicable):
Latest

How reproducible:
Very

Steps to Reproduce:
1. Use trackpad on Lenovo T42, watch cursor location
2. Especially bad with Firefox vertical scroll causing whole screen to jitter


Expected results:
No jittering of cursor location

Additional info:
Recommended feature 
- Add averaging filter slider to MousePreferences/General to adjust the number of last mouse/trackpad X-Y coordinates to average. i.e. No averaging, average last 2, average last 3, average last 4, etc.
- Add hysteresis slider to cursor movement. Dome move cursor unless coordinates have changed by more than X. X=0,1,2,3 

I just installed Fedora14. This is the first time I have been able to install a disto without hanging. This is an amazing disto. Perfect except for this little annoyance. I'm happy to assist with the coding fix. Jut give me guidance of where to start. I'm a newbi, but could figure it out if pointed in the right direction.

Comment 1 Gianluca Sforna 2010-12-23 17:05:52 UTC
Uhm. I don't think gpointing-device-settings is the right component for this request. Sounds more like an issue for the input layer, at the xorg or kernel level.

Comment 2 Richard Burton 2010-12-23 19:25:46 UTC
Yes, I think you are right. I found the following about tslib. Is this what Fedora 14 uses? Looks like the dejitter default is not optimal for Lenovo laptops (maybe not in general)? Note: this has been an issue for all Linux distos evaluated on my Lenovo T42.

1. How to change immediately if easy?
2. Does a general release of an improvement make sense to improve community happiness about Fedora?
3. Who would be the owner of such a release change?

-----------------------------
The idea of tslib is to have a core library that provides standardised services, and a set of plugins to manage the conversion and filtering as needed.

The plugins for a particular touchscreen are loaded automatically by the library under the control of a static configuration file, /etc/ts.conf. /etc/ts.conf gives the library basic configuration information. Each line specifies one module, and the parameters for that module. The modules are loaded in order, with the first one processing the touchscreen data first. For example:

      module_raw input
      module variance delta=30
      module dejitter delta=100
      module linear
----------------------------

Comment 3 Gianluca Sforna 2010-12-24 11:41:53 UTC
Richard, it seems this bug is present upstream (in xorg), that's why you experienced it in all distro you tried.

So, to have higher chances to fix it in Fedora _and_ for everyone else, would you submit the same upstream please?

Specifically:
https://bugs.freedesktop.org/enter_bug.cgi?product=xorg&component=Input%2Fsynaptics

thanks in advance for your help

Comment 4 Richard Burton 2010-12-24 19:32:43 UTC
Thanks. Submitted.


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