<html>
<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [PNV] N450 and D510 machines get stuck in igt@gem_ringfill@basic-default-hang"
href="https://bugs.freedesktop.org/show_bug.cgi?id=99093">99093</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[PNV] N450 and D510 machines get stuck in igt@gem_ringfill@basic-default-hang
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>DRI git
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>major
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tomi.p.sarvela@intel.com
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Pineview testshosts I've tested seem to hang forever in following code when
tested with igt@gem_ringfill@basic-default-hang. Comment from vsyrjala implied
that the GPU hang reset messes PLL when done in wrong time.
No dmesg is left behind. This spot was found with gratuitous adding of
DRM_DEBUGs.
The bug has been around in drm-intel-nightly / drm-tip for at least two months.
drivers/gpu/drm/i915/i915_irq.c:i915_get_vblank_counter():
/*
* High & low register fields aren't synchronized, so make sure
* we get a low value that's stable across two reads of the high
* register.
*/
do {
high1 = I915_READ(high_frame) & PIPE_FRAME_HIGH_MASK;
low = I915_READ(low_frame);
high2 = I915_READ(high_frame) & PIPE_FRAME_HIGH_MASK;
} while (high1 != high2);</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
<li>You are the QA Contact for the bug.</li>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>