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<base href="https://bugs.freedesktop.org/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [915 Haswell ULT Asus UX302LA/LG] eDP bpp clamping results in blank screen"
href="https://bugs.freedesktop.org/show_bug.cgi?id=73567">73567</a>
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Summary</th>
<td>[915 Haswell ULT Asus UX302LA/LG] eDP bpp clamping results in blank screen
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Reporter</th>
<td>albaguirre@gmail.com
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=91970" name="attach_91970" title="Test ignoring bpp clamping">attachment 91970</a> <a href="attachment.cgi?id=91970&action=edit" title="Test ignoring bpp clamping">[details]</a></span> <a href='page.cgi?id=splinter.html&bug=73567&attachment=91970'>[review]</a>
Test ignoring bpp clamping
I have an ASUS UX302LA laptop running Ubuntu 14.04 daily build. I've switched
the kernel to the latest drm-intel-nightly from here:
<a href="http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/current/">http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/current/</a>)
Any sequence that turns off/on the panel (suspend/resume, modesetting) results
in a blank screen.
I narrowed it down to the clamping code in intel_dp.c after going through this
old bug thread (see attached patch)
<a href="https://bugzilla.kernel.org/show_bug.cgi?id=59841">https://bugzilla.kernel.org/show_bug.cgi?id=59841</a>
When ignoring the clamping - no blank screen issues occur.
The hack implemented in intel_dp.c:
commit c6cd2ee2d59111a07cd9199564c9bdcb2d11e5cf
Author: Jani Nikula <<a href="mailto:jani.nikula@intel.com">jani.nikula@intel.com</a>>
Date: Mon Oct 21 10:52:07 2013 +0300W
drm/i915/dp: workaround BIOS eDP bpp clamping issue
Is not effective on the UX302LA/LG - from logs it looks like
intel_dp_get_config is never called - any idea why?</pre>
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