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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Screen flickering at low resolution when monitor is attached via VGA dongle to DVI port"
href="https://bugs.freedesktop.org/show_bug.cgi?id=83184">83184</a>
</td>
</tr>
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<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Summary</th>
<td>Screen flickering at low resolution when monitor is attached via VGA dongle to DVI port
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Rainer.Koenig@ts.fujitsu.com
</td>
</tr>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Component</th>
<td>DRM/Radeon
</td>
</tr>
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<th>Product</th>
<td>DRI
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=105377" name="attach_105377" title="dmesg output with drm debug information">attachment 105377</a> <a href="attachment.cgi?id=105377&action=edit" title="dmesg output with drm debug information">[details]</a></span>
dmesg output with drm debug information
Encountered a strange problem with Radeon HD 6250 (or HD 6310) on a Fujitsu
D3003-S1x mainboard. Occurs with every tested linux distribution and older and
newer kernels.
Problem occurs only when a monitor is attached via VGA to the DVI port. If the
monitor is attached via DVI then the problem does not occur.
Problem is that
- Monitor is flickering sporadically
- Monitor resolution is fixed to 1024x768 instead of higher resolutions that
are possible
- xrandr shows 2 monitors while just one monitor is attached
Tried to debug this with kernel parameter drm.debug=14 (dmesg log is attached)
and found the following messages that would explain the flickering screen.
[ 4.098364] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off DVI-I-1
[ 4.098369] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
VGA-1
[ 4.219817] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off VGA-1
[ 4.219830] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
DVI-I-1
[ 4.231344] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off DVI-I-1
[ 4.231350] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
VGA-1
[ 13.949336] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off VGA-1
[ 13.949350] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
DVI-I-1
[ 13.967886] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off DVI-I-1
[ 13.967891] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
VGA-1
[ 14.023332] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off VGA-1
[ 14.023345] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
DVI-I-1
[ 14.056688] [drm:radeon_connector_analog_encoder_conflict_solve] 1:
conflicting encoders switching off DVI-I-1
[ 14.056694] [drm:radeon_connector_analog_encoder_conflict_solve] in favor of
VGA-1
The problem is still to find the root cause that leads to the issue of having
"conflicting encoders". Any idea what could cause this behaviour?
Regards
Rainer</pre>
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