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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SKL][REGRESSION][BISECTED] Dropped frames and FIFO underruns when moving mouse across (plane?) boundary"
href="https://bugs.freedesktop.org/show_bug.cgi?id=97878">97878</a>
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<th>Summary</th>
<td>[SKL][REGRESSION][BISECTED] Dropped frames and FIFO underruns when moving mouse across (plane?) boundary
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>michael@michaelmarley.com
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<pre>Created <span class=""><a href="attachment.cgi?id=126674" name="attach_126674" title="Output of dmesg with the DRM debugging turned on">attachment 126674</a> <a href="attachment.cgi?id=126674&action=edit" title="Output of dmesg with the DRM debugging turned on">[details]</a></span>
Output of dmesg with the DRM debugging turned on
After upgrading from kernel 4.7.4 to 4.8-rc7, several frames are dropped
(resulting in jerky graphics and a jerky mouse cursor) when the mouse passes
over a boundary about a hundred pixels from the right side of my left monitor
(DP-1). Sometimes, especially if the system is under heavy load, a FIFO
underrun on one of the monitors will occur as well.
My system is a Lenovo m900 with a "Intel(R) Core(TM) i5-6500T CPU @ 2.50GHz"
processor. It is running kernel 4.8.0-040800rc7-lowlatency (as downloaded from
<a href="http://kernel.ubuntu.com/~kernel-ppa/mainline/">http://kernel.ubuntu.com/~kernel-ppa/mainline/</a>) on Kubuntu 16.10 amd64. The
system has two monitors, both Dell U2312HMs connected by DisplayPort. The left
monitor is connected to DP-1 and the right monitor to DP-2. I have also tried
connecting the monitors using DisplayPort-DVI adapters, but this does not
affect the issue.
I bisected the issue and found that it was introduced with commit
9909113cc48a7ce6e772573e3cc82a3f03ffa8ef
(<a href="https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/i915?id=9909113cc48a7ce6e772573e3cc82a3f03ffa8ef">https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/i915?id=9909113cc48a7ce6e772573e3cc82a3f03ffa8ef</a>).
However, reverting the commit isn't a possibility because that causes severe
problems with mouse cursor updates (a cursor trail getting stuck on the screen
and often flickering rapidly.)</pre>
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