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<base href="https://bugs.freedesktop.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - No image via KVM switch. USB-C->dual DisplayPort->KVM"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109829">109829</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>No image via KVM switch. USB-C->dual DisplayPort->KVM
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>XOrg git
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>major
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>stuart@eightfivelabs.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=143523" name="attach_143523" title="dmesg">attachment 143523</a> <a href="attachment.cgi?id=143523&action=edit" title="dmesg">[details]</a></span>
dmesg
Hi all,
I have a NUC7i7BNH with the latest BIOS (0062) running Ubuntu 18.04 (uname -r =
4.18.0-15-generic). I have the NUC connected via USB-C to a dual DisplayPort
adapter, to an Avocent SV340D KVM. Also tried kernel v5.0-rc7.
If I have the KVM on the switch for the NUC, everything works great. If I
switch the KVM to another channel, and then switch back to the NUC, I only get
black screens. The only solution is to hard reboot the NUC.
This relates to a bug I raised on
<a href="https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1816269">https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1816269</a>.
Specifically [ 135.089830] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
*ERROR* CPU pipe A FIFO underrun followed by a lot of thunderblot hotplug
messages.</pre>
</div>
</p>
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