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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>high
</td>
</tr>
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [ILK Bisected]igt/kms_flip subcases causes "[drm:ilk_display_irq_handler] *ERROR* Pipe A FIFO underrun ""
href="https://bugs.freedesktop.org/show_bug.cgi?id=84161">84161</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>[ILK Bisected]igt/kms_flip subcases causes "[drm:ilk_display_irq_handler] *ERROR* Pipe A FIFO underrun "
</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>All
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jinxianx.guo@intel.com
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</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>==System Environment==
--------------------------
Regression: Yes.
Non-working platforms: ILK
==kernel==
--------------------------
origin/drm-intel-nightly:c5660b4ad395f1e34eacc22cf81c687edfc9c83c(fails)
drm-intel-nightly: 2014y-09m-19d-18h-12m-22s UTC integration manifest
==Bug detailed description==
-----------------------------
igt/kms_flip subcases causes "[drm:ilk_display_irq_handler] *ERROR* Pipe A FIFO
underrun "
Case list:
igt/kms_flip/2x-flip-vs-expired-vblank
igt/kms_flip/2x-flip-vs-expired-vblank-interruptible
==Reproduce steps==
----------------------------
1. ./kms_flip --run-subtest 2x-flip-vs-expired-vblank
==Bisect results form [PRTS][auto-bisect]==
----------------------------
commit cf1a5cccaae1ac843b6042178662820f1fb58dea
Author: Mario Kleiner <<a href="mailto:mario.kleiner.de@gmail.com">mario.kleiner.de@gmail.com</a>>
AuthorDate: Sat Sep 13 18:25:54 2014 +0200
Commit: Daniel Vetter <<a href="mailto:daniel.vetter@ffwll.ch">daniel.vetter@ffwll.ch</a>>
CommitDate: Mon Sep 15 15:47:19 2014 +0200
drm: Don't update vblank timestamp when the counter didn't change
If we already have a timestamp for the current vblank counter, don't
update it with a new timestmap. Small errors can creep in between two
timestamp queries for the same vblank count, which could be confusing to
userspace when it queries the timestamp for the same vblank sequence
number twice.
This problem gets exposed when the vblank disable timer is not used
(or is set to expire quickly) and thus we can get multiple vblank
disable<->enable transition during the same frame which would all
attempt to update the timestamp with the latest estimate.
Testcase: igt/kms_flip/flip-vs-expired-vblank
Signed-off-by: Ville Syrjälä <<a href="mailto:ville.syrjala@linux.intel.com">ville.syrjala@linux.intel.com</a>>
Reviewed-by: Mario Kleiner <<a href="mailto:mario.kleiner.de@gmail.com">mario.kleiner.de@gmail.com</a>>
v2:Mario: Trivial rebase on top of current drm-next (13-Sep-2014)
Signed-off-by: Mario Kleiner <<a href="mailto:mario.kleiner.de@gmail.com">mario.kleiner.de@gmail.com</a>>
Signed-off-by: Daniel Vetter <<a href="mailto:daniel.vetter@ffwll.ch">daniel.vetter@ffwll.ch</a>></pre>
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