<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Radeon R9 390X regression - No output (CVT) or corruption (CVT-R) at 4096x2160@60Hz over DisplayPort"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101290">101290</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Radeon R9 390X regression - No output (CVT) or corruption (CVT-R) at 4096x2160@60Hz over DisplayPort
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>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/Radeon
</td>
</tr>
<tr>
<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>freedesktop@nuclearsunshine.com
</td>
</tr></table>
<p>
<div>
<pre>I had thought I had filed this bug a long time ago on here, but I can't find
it...
Graphics card: Radeon R9 390X (Saphhire 11241-04-20G)
Display: LG 31MU97 (via DisplayPort)
With Linux 4.4.x, 4096 x 2160 @ 60 Hz progressive output was working with
standard CVT timing.
With Linux 4.5.x onwards, standard CVT timing at that resolution fails (no
signal) with the following dmesg output:
kernel: [drm:radeon_dp_link_train [radeon]] *ERROR* channel eq failed
kernel: [drm:radeon_dp_link_train [radeon]] *ERROR* channel eq failed: 5 tries
CVT-R timing results in output, but with a flickering/corrupted full-height
band down the right hand side (it approximates the intended output, but pixels
seem be to be corrupt in single-pixel horizontal bands and/or flicker in
horizontal single-pixel bands) It could be complete coincidence, but the width
of the corrupt band seems to be the difference in width vs. 3840x2160, i.e.
aobut 256 pixels. With this timing there are no messages in dmesg.
There's a downstream Fedora bug report here:
<a href="https://bugzilla.redhat.com/show_bug.cgi?id=1353341">https://bugzilla.redhat.com/show_bug.cgi?id=1353341</a></pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
</ul>
</body>
</html>