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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 - MST not being enabled on Haswell host"
href="https://bugs.freedesktop.org/show_bug.cgi?id=87917">87917</a>
</td>
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<th>Summary</th>
<td>MST not being enabled on Haswell host
</td>
</tr>
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<th>Product</th>
<td>xorg
</td>
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<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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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>Driver/intel
</td>
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<th>Assignee</th>
<td>chris@chris-wilson.co.uk
</td>
</tr>
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<th>Reporter</th>
<td>steven@uplinklabs.net
</td>
</tr>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=111587" name="attach_111587" title="dmesg 3.18.1, unhappy MST">attachment 111587</a> <a href="attachment.cgi?id=111587&action=edit" title="dmesg 3.18.1, unhappy MST">[details]</a></span>
dmesg 3.18.1, unhappy MST
I've got a GIGABYTE Brix Pro i7-4770R box with a Mini DisplayPort output.
Attached to that port I have a Dell UP2414Q 4K monitor, with DisplayPort 1.2
mode enabled. On Windows I'm able to use the native MST-backed 60Hz 4K
resolution without issues.
On Linux (3.18.1), I'm having troubles getting that to happen.
First of all, X11 is starting at 1024x768 resolution, and the kernel said this
about it:
[ 2.631515] [drm] Cannot find any crtc or sizes - going 1024x768
Once X11 is started, I'm able to see the two halves of the display in my KDE
monitor preferences (DP1-8 and DP1-9, where DP1-9 is the left half of the
display). I can also set both of them to 1920x2160 and configure the
positioning such that the two halves are treated as separate monitor outputs
side-by-side. But ideally this should be discovered as one 3840x2160 monitor,
on a single DisplayPort output. That would also make it so that my X11 WM would
treat it as a single desktop.
I've booted my kernel with drm.debug=6, and attached it for inspection.</pre>
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