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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - ZaphodHeads + TearFree cause what looks like severe double buffering synchronization problems"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104343">104343</a>
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<th>Summary</th>
<td>ZaphodHeads + TearFree cause what looks like severe double buffering synchronization problems
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<th>Product</th>
<td>xorg
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>Driver/intel
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<th>Assignee</th>
<td>chris@chris-wilson.co.uk
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<th>Reporter</th>
<td>werner@almesberger.net
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<p>
<div>
<pre>My setup: CPU is i7-7700K using build-in GPU (HD 630), no graphics card, no
overclocking or particularly unusual setup.
Displays are three in total: HD (HDMI), 4K (DP), HD (DVI-HDMI). This
configuration worked under Ubuntu 17.04 but the middle screen (4K) became
unusable after upgrading to 17.10.
The effects look like faulty coordination between drawing and buffer switching.
I made a short video:
<a href="https://almesberger.net/paste/weird-gfx-raiPhie8.mp4">https://almesberger.net/paste/weird-gfx-raiPhie8.mp4</a>
Note:
- this happens with and without window manager (fvwm)
- when trying to play video with mplayer, the screen content barely changed.
The video was not shown.
- SolveSpace (3D CAD) performed almost normally for anything 3D, but menus and
other text has issues similar to the ones shown in my video.
- similar symptoms continued also when I changed the resolution of the 4K
display to 1920x1080 in xorg.conf
- the two HD screens (:0 and :0.2) worked fine all the time
xorg.conf:
<a href="https://almesberger.net/paste/xorg-eiTahF5A.conf">https://almesberger.net/paste/xorg-eiTahF5A.conf</a>
Xorg.0.log:
<a href="https://almesberger.net/paste/Xorg.0-Jahbie1O.txt">https://almesberger.net/paste/Xorg.0-Jahbie1O.txt</a>
dmesg:
<a href="https://almesberger.net/paste/aiPo3ae8.txt">https://almesberger.net/paste/aiPo3ae8.txt</a>
Chris Wilson (ickle) remarked on #intel-gfx that ZaphodHeads and TearFree were
an unusual combination and suggested I try to disable TearFree in xorg.conf.
After disabling it in all three Device sections, the problem disappeared and
all seems fine so far (tried xterm, fvwm, chromium, solvespace, and mplayer).</pre>
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