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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 --- - Recover from missing DRM completion events"
href="https://bugs.freedesktop.org/show_bug.cgi?id=83884">83884</a>
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<th>Assignee</th>
<td>wayland-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Summary</th>
<td>Recover from missing DRM completion events
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>Linux (All)
</td>
</tr>
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<th>Reporter</th>
<td>ppaalanen@gmail.com
</td>
</tr>
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<th>Hardware</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Component</th>
<td>weston
</td>
</tr>
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<th>Product</th>
<td>Wayland
</td>
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<p>
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<pre>Add a watchdog to the DRM backend that will recover Weston, if the DRM page
flip events stop coming.
Weston relies on those events, and will normally not repaint until the previous
update has been acked. However, on buggy DRM drivers, and now that we are
getting closer to the universal planes and atomic mode setting and page
flipping framework, it is quite likely that some drivers are sometimes buggy.
Recovering from buggy drivers while still clearly signalling the failure should
help developers in testing their drivers.
How to recover?
Some options:
- gracefully quit Weston with an error
- fall back to immediate, timer throttled display updates (drmModeSetCrtc /
drmModePageFlip without events) and hope it works
Need to take care to not cause the watchdog to trigger during e.g. VT-switched
away, or during high load.</pre>
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</p>
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