Debian 8.1 lxqt 2015-07-19 4DCAPE-43T touchscreen issues

I'm running on a beaglebone black rev B using the micro-sd standalone version of Debian

Linux beaglebone 4.1.3-bone14 #1 Thu Jul 23 00:04:37 UTC 2015 armv7l GNU/Linux

The touch mouse is very erratic in this release.
During the calibration routine the mouse jumps about.
The touch will result in the mouse bouncing from the approximate touch point to a random point, in a flickering action.
Releasing the touch causes the mouse to rest in a random position.
After calibration, the touch screen is still not calibrated.
Touching on a clickable item on the screen will result in the same weirdness, the mouse will jump form the uncalibrated touch point to a random position and back in a flickering motion.
The touch seems to be a "right click" instead of a "left click", or an "all-click" (not sure because sometimes you can get the menu to pop up).
It is difficult to get the menus to respond to the mouse events.
Anyone have ideas on how to get the touchscreen to behave properly?

Anyone have ideas on how to get the touchscreen to behave properly?

Not personally, no. But I do know that this topic has been talked about on the groups a few times before - In the past. I want to say that at least one of the posts was resolved, but it’s been a while.

Perhaps some good google-fu will pay off ?

Let me stretch first before Google-Fu....
Ha! Woo! Wa!
Ouchie! I pulled a muscle somewhere!
Again, I lack in skill and dexterity. :frowning:

Searches for Debian 4DCAPE jessie lxqt (and various combinations) result in the same info.
Most problems talk about calibration and kernel dumps.
This release does not have issues with basic touchscreen operation and calibration operation.
Or, I should clarify, the calibration program runs and a touch results in a response.

However, there is an issue with touch with positioning and which button is pressed and how many times.
If I touch and drag, it acts like a right-click hold (with releases) and drag (selects a region of the screen)
Despite running touch calibration, it's not calibrated. Maybe because during calibration the cursor jumps about on the screen?
A touch on a control results in several mouse events - some left clicks, some right clicks (menus flicker, refuse to stay up)
It seems like a debouncing issue.

If I plug in a USB mouse, the mouse works as expected.
Positioning works well. Clicks respond as expected.

If I put Debian 7.8 lxde on the same hardware, the touchscreen works perfectly.
Positioning works well. Clicks respond as expected.

Maybe I'm just not finding the post or google result that talks about the resolution to this issue.

Our 'new' v4.1.x kernel just needs some tuning on the adc.. We've had
about 3 years to tune the 3.8 kernel for touchscreen, most of the
patches went mainline.

Feel free to jump in and help. :wink:


Thanks Robert.
I can be patient.
I just needed to know if this is a known issue and if it was fixable with a configuration file or install program.
I would be happy to help if I can, but I am not that familiar with kernel code.
I am experienced in C, C++, C#, Java.

So the driver is here:

The main read is here:

we mostly read the raw values, with no real filtering..


I'll spend a little time and see if I can get a module to compile and test some ideas.
I doubt I'll be able to improve on it, but it looks interesting. :slight_smile:

Sorry to hijack the thread but I editted the touchscreen driver.
I inserted the code from the arago project and on my 4D LCD70T it’s a huge improvement.
A lot less jitter.

A link to the patch file: