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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 --- - [Bisected BDW drm-intel-fixes] Enable PSR feature by insert kernel parameter "i915.enable_psr=1", will cause x fail to start"
href="https://bugs.freedesktop.org/show_bug.cgi?id=76345">76345</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>[Bisected BDW drm-intel-fixes] Enable PSR feature by insert kernel parameter "i915.enable_psr=1", will cause x fail to start
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Severity</th>
<td>major
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Reporter</th>
<td>wendy.wang@intel.com
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86 (IA32)
</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>By kernel default setting, PSR feature is false, we need insert
"i915.enable_psr=1" parameter in kernel to enable the PSR in kernel, after
reboot, run xinit &, x fail to start.
this issue happened from 2014_03_07 nightly branch to the latest nightly
branch, before that no such issue.
Do bisect find drm-intel-fixes branch,
24bd9bf54d45d28089251cdf62bf14323d1aa827 is the first bad commit, revert this
commit, issue disappeared.
This issue found on BDW platform, did not reproduce on HSW platform.
commit 24bd9bf54d45d28089251cdf62bf14323d1aa827
Author: Ben Widawsky <<a href="mailto:benjamin.widawsky@intel.com">benjamin.widawsky@intel.com</a>>
Date: Tue Mar 4 22:38:10 2014 -0800
drm/i915: Fix PSR programming
| has a higher precedence than ?. Therefore, the calculation doesn't do
at all what you would expect. Thanks to Ken for convincing me that this
was indeed the issue. Send me back to C programmer school, please.
I'm sort of surprised PSR was continuing to work for people. It should
be broken IMO (and it was broken for me, but I had assumed it never
worked).
Regression from:
commit ed8546ac1f99b850879f07b1e9b06b42fb0a36d9
Author: Ben Widawsky <<a href="mailto:benjamin.widawsky@intel.com">benjamin.widawsky@intel.com</a>>
Date: Mon Nov 4 22:45:05 2013 -0800
drm/i915/bdw: Support eDP PSR
Cc: Rodrigo Vivi <<a href="mailto:rodrigo.vivi@gmail.com">rodrigo.vivi@gmail.com</a>>
Cc: Kenneth Graunke <<a href="mailto:kenneth.w.graunke@intel.com">kenneth.w.graunke@intel.com</a>>
Cc: Art Runyan <<a href="mailto:arthur.j.runyan@intel.com">arthur.j.runyan@intel.com</a>>
Reported-by: "Kumar, Kiran S" <<a href="mailto:kiran.s.kumar@intel.com">kiran.s.kumar@intel.com</a>>
Cc: <a href="mailto:stable@vger.kernel.org">stable@vger.kernel.org</a> [v3.13+]
Signed-off-by: Ben Widawsky <<a href="mailto:ben@bwidawsk.net">ben@bwidawsk.net</a>>
Signed-off-by: Jani Nikula <<a href="mailto:jani.nikula@intel.com">jani.nikula@intel.com</a>>
:040000 040000 af3b065bcd133817f46c1c1e6328db8cc1767095
c7b6f61027f166bb5a712201a2bd2d3997adac6e M drivers</pre>
</div>
</p>
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