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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - DPCD backlight causes black screen on ThinkPad X1 Carbon 4th Gen"
href="https://bugs.freedesktop.org/show_bug.cgi?id=101619">101619</a>
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<th>Summary</th>
<td>DPCD backlight causes black screen on ThinkPad X1 Carbon 4th Gen
</td>
</tr>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Status</th>
<td>NEW
</td>
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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
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Reporter</th>
<td>david.weinehall@intel.com
</td>
</tr>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=132294" name="attach_132294" title="dmesg with drm.debug=0xE">attachment 132294</a> <a href="attachment.cgi?id=132294&action=edit" title="dmesg with drm.debug=0xE">[details]</a></span>
dmesg with drm.debug=0xE
With DPCD backlight enabled (default as of a few days ago in drm-tip), the
backlight no longer works properly on my ThinkPad X1 Carbon 4th Gen (2560x1440
display option).
If I pass i915.enable_dpcd_backlight=0 on boot the backlight behaves as it
should (because of this workaround I'm filing the issue as normal rather than
major).</pre>
</div>
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