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Old 03-21-2016, 03:25 AM   #1
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Registered: Feb 2016
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Debugging Xorg

I am stucked for a month with video example given in Qt Video Overview.

I tried that code, but only I get is blank square (QWidget). I am using GStreamer0.10 for media playback over Qt5. I also played video with gst-launch-0.10 command and it works okay, but I cannot determine what's happening in Qt and why it won't work?

I looked in error log of X Server, located in /etc/X11/Xorg.0.log, and when I use fbdev as a display driver configured in /etc/X11/xorg.conf it shows me the error:

"FBDEV(0): FBIOPUTCMAP: Invalid argument"
when I use modesetting driver everything acts the same but no errors. I figured out that when I delete xorg.conf file and start X server again, video works but with lack of colors and with flickering also example works well on my Ubuntu VM and via vnc client. Every advice and help will be appreciated.

Target machine: BeagleBone Black

Distribution: Debian Jessie 8.2

Kernel Version: 4.1.15-ti-rt-r43

List of available drivers in /usr/lib/xorg/modules/drivers:,,,,,,,,

Here is a full error log from Xorg when I try to launch my Qt application on BeagleBone Black under Debian Jessie 8.2 ->

xorg.conf file from /etc/X11 ->
Old 03-22-2016, 11:26 PM   #2
Registered: Mar 2011
Location: Sutton, MA. USA
Distribution: MINT Debian, Angstrom, SUSE, Ubuntu
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I've never gotten the frame buffer form to work. I always use an XServer but with no Window manager and then make my Qt application frameless and full screen.

We bought Qt way, way ago when it was sold Digia or whoever may have been before them. Paid like $2,000 for it and we could request and get support. I opened a lot of requests and they literally helped me with all of them, except getting it working on the frame buffer. They could on certain full x86 boxes and demonstrated that for me, but it really depended on the bridge chip being used, and literally depended on the motherboard. I decided it was never worth my time and my company's time to wait for all that to work and we went instead with XServer with No DM.

There are people who have gotten the frame buffer to work. There are people who have gotten it to "work" but not with Qt. And there are people who have actually gotten it to work with Qt, but I believe those two categories decrease in size as you go from "using the frame buffer in general" to "using the frame buffer for Qt and graphics" Those who use the frame buffer sometimes just do text, not pixel graphics. You are using an ARM and a hobbyist ARM. Don't do it, I say. Check the Beagle forums, the main guy (forget his name) was still very active on the forums up to last year and probably still is. Robert something or other. He either can help you, versus not. If he can't, then the only other recommendation would be to go to a commercially supplied ARM SOM from someone where you've paid for their product and support and can get them to help you; however check first even if they claim framebuffer support, make them prove that to you. A lot of companies just put that in there and when you get involved and ask for real, they get all ... spotty with their answers.

Just my $2,000.00!!!

There are also a few threads in LQ about framebuffer. Likely you'll see me having sounded off in some of those threads ere long ago.


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