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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 - Acer XB270HU I2C and EDID not working on iGPU + radeon/amdgpu"
href="https://bugs.freedesktop.org/show_bug.cgi?id=102069">102069</a>
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</tr>
<tr>
<th>Summary</th>
<td>Acer XB270HU I2C and EDID not working on iGPU + radeon/amdgpu
</td>
</tr>
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<th>Product</th>
<td>DRI
</td>
</tr>
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<th>Version</th>
<td>XOrg git
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
</td>
</tr>
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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>DRM/Intel
</td>
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>gerben@daybyday.nl
</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=133284" name="attach_133284" title="ddcutil on intel">attachment 133284</a> <a href="attachment.cgi?id=133284&action=edit" title="ddcutil on intel">[details]</a></span>
ddcutil on intel
I have a desktop with a Samsung SA850HD and an Acer XB270HU, both connected
with DP. The Acer screen does not return any EDID and reports I2C nack when
plugged in, both on the intel iGPU as well as on a HD7850 card. The Samsung
screen works great. It also doesn't matter if I plug in just the Acer, it
happens in single and multimonitor mode (for amdgpu/radeon).
What's more, the Acer screen works perfectly fine when plugged into a GTX980
with Nouveau driver (on another box booted with Ubuntu 17.04 live cd). So the
screen itself is fine. It also reports all valid data with softMCCS in Windows;
full DDC control is available there.
This is on 4.12.5 x86_64, Debian sid. Relevant smoking gun on intel:
[ 74.733494] [drm:intel_dp_start_link_train] Clock recovery check
failed, cannot continue channel equalization
[ 74.737037] [drm:drm_dp_i2c_do_msg] I2C nack (result=0, size=0
I've attached logs generated with ddcutil for each card which will show
summarized system info; I will attach full drm.debug=0xe dmesg shortly, please
advise if more info is needed.</pre>
</div>
</p>
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