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Hi,
on my new laptop with Intel graphics chip there is an issue with redraws. When some area in a program is redrawn, the two bottommost rows of pixels are not updated. This causes artifacts which stay there until a redraw of a larger region happens. As an example, see this screenshot where I moved the cursor from the bottom to the top with line highlighting activated, leaving traces of the highlighting and the cursor:
https://dl.dropboxusercontent.com/u/211 … ug_sna.png
I already tried switching between sna and uxa acceleration modes, with no success (the underscore in the screenshot was just for testing, this is not the problem). The screenshot shows the effect with sna mode. With uxa it is the same, just inverted (not updating the two topmost rows).
Has anyone seen this and knows a fix, or something I could try?
Some information about my system:
The laptop has an i7-3667U processor, so it uses an Intel HD Graphics 4000 unit.
The output of lspci | grep VGA is:
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
I use KDE, however the artifacts also appear in non-KDE applications.
The system should be up to date.
Of course I could also post more information if you tell me which could be relevant.
I haven't found information about such a problem with Google yet.
Thanks in advance for any hints.
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If you are using Gnome, try putting the following in the file /etc/environment and log out/log in. Create the file if one does not exist.
CLUTTER_PAINT=disable-clipped-redraws:disable-cullinghttps://bugzilla.gnome.org/show_bug.cgi?id=657071#c2
EDIT: Sorry, I see you use KDE. In the KDE compositor, try using only Vsync and uncheck "Use OpenGL 2 Shaders".
EDIT2: You might have better results with a different kernel. Some kernel versions implement Intel graphics acceleration better than others. It is also possible that you have a hardware problem, but I would suspect a software issue first.
Last edited by David Batson (2013-08-07 19:06:05)
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Unchecking "Use OpenGL 2 Shaders" in System Settings > Desktop Effects > Advanced fixed it, thanks a lot! I added this hint to the Troubleshooting section of the KDE wiki article, in the assumption that this is not too specific to be put there.
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Actually this conclusion was a bit too quick: after a restart, the problem occurred again. It turned out that the value of the setting is not relevant, it is the act of changing the setting which removes the problem until the next restart (and possibly it works with other settings too). Now it would be good to find out if there is a persistent solution ...
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