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<base href="https://bugs.freedesktop.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - DVI port is not detecting connected monitor with 4.16.0+ kernel and amdgpu.dc=1 set"
href="https://bugs.freedesktop.org/show_bug.cgi?id=105971">105971</a>
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</tr>
<tr>
<th>Summary</th>
<td>DVI port is not detecting connected monitor with 4.16.0+ kernel and amdgpu.dc=1 set
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>OS</th>
<td>Linux (All)
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>medium
</td>
</tr>
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<th>Component</th>
<td>DRM/AMDgpu
</td>
</tr>
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<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>sass.joel@gmail.com
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=138731" name="attach_138731" title="dmesg output from amdgpu.dc=0 switch">attachment 138731</a> <a href="attachment.cgi?id=138731&action=edit" title="dmesg output from amdgpu.dc=0 switch">[details]</a></span>
dmesg output from amdgpu.dc=0 switch
Hello. I'm trying to get 4 monitors working on the same desktop. Video card is
a Radeon RX560.
root@nope:/tmp# lsb_release -a
LSB Version:
core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch
Distributor ID: Ubuntu
Description: Ubuntu 16.04.4 LTS
Release: 16.04
Codename: xenial
root@nope:/tmp# uname -a
Linux nope 4.16.0+ #1 SMP Mon Apr 2 15:52:14 CEST 2018 x86_64 x86_64 x86_64
GNU/Linux
With kernel switch amdgpu.dc=1, DVI port doesn't detected connected monitor,
but displayport MST is detected and utilized properly, allowing me to output
video to three monitors from a single displayport.
With kernel switch amdgpu.dc=0, DVI port properly detects connected monitor,
but displayport MST is not detected. Instead, displayport MST acts as a single
output, and video output is mirrored to all three connected monitors.
This appears to be a kernel issue. Kernel was retrieved from git repo
github.com/M-Bab/linux-kernel-amdgpu-binaries
I'm running the AMDGPU.UBUNTU kernel on that repo.
I'll attach dmesg, xrandr and Xorg.0.log output from both kernel switches.
I'm running amdgpu.dc_log=1 kernel switch for verbose logging.</pre>
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