Touchscreen working in live system but not after installation

[Uwe]

When I start Ubuntu 16.04 from USB on a Dell Venue 11 Pro 7139 the touchscreen works well. After installing and re-starting the system the touch support is completely gone. As far as I can see, all modules are loaded in life system as well as in installed system. There seem to be no differences in kernel versions and start options as well.

The Xorg-logs of the live and the installed system show no major differences except different numbers of the event-files in /dev/input. Both systems recognize the Synaptics device as touchscreen: (II) evdev: SYNA7500:00 06CB:3AF0: Configuring as touchscreen.

The main difference are thousands of evbug entries like the following two in the kern.log of the installed system while none are reported in the live system.

Apr 25 14:10:05 uwe-Venue-11-Pro-7139 kernel: [ 61.288764] evbug: Event. Dev: input7, Type: 0, Code: 0, Value: 0
Apr 25 14:10:05 uwe-Venue-11-Pro-7139 kernel: [ 61.406747] evbug: Event. Dev: input7, Type: 3, Code: 57, Value: 44.

They appear every time I use the touchpad. So I think the detection of input devices is kind of faulty in the installed system.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1574594/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Paul White (paulw2u)]

According to https://wiki.ubuntu.com/Bugs/FindRightPackage#Hardware_Malfunctions this bug should be filed against the kernel.

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1574594

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]