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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [BXT-P] i915 driver overwrites the DDI PHY register for the 1366x78 panel with incorrect values"
href="https://bugs.freedesktop.org/show_bug.cgi?id=95476">95476</a>
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<th>Summary</th>
<td>[BXT-P] i915 driver overwrites the DDI PHY register for the 1366x78 panel with incorrect values
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>DRI git
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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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
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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>
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<th>Reporter</th>
<td>tarun.vyas@intel.com
</td>
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=123891" name="attach_123891" title="Full dmesg log">attachment 123891</a> <a href="attachment.cgi?id=123891&action=edit" title="Full dmesg log">[details]</a></span>
Full dmesg log
In the APL platforms, the firmware enables the 1366x768 panels by correctly
programming the DDI PHY registers, but this leads to a PHY state mismatch
according to the i915 driver because the driver expects to read a value from
the PHY registers that differs from what was programmed by the firmware. Hence,
the i915 driver goes ahead and reprograms the PHY, incorrectly, causing the DP
link training to fail. The i915 driver will need modifications to correct this
behavior. Filing this bug to track those modifications.
Steps to reproduce:
1. Connect a 1366x768 panel as an eDP to a APL system.
2. Boot the system with dinq kernel.
3. The 1366x768 panel will fail to come up.
Reproduciblity: 100%
System architecture: x86_64
Kernel version: 4.6.0-01610-g68c6a6d-dirty
Linux distro: Chromium OS
Display Connector: eDP
Machine info:</pre>
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