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      <base href="https://bugs.freedesktop.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Pageflip completion event has impossible msc related lockups"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=112255">112255</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Pageflip completion event has impossible msc related lockups
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>xorg
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>FreeBSD
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>not set
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>not set
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Driver/AMDgpu
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>xorg-driver-ati@lists.x.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>steve@mouf.net
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>xorg-team@lists.x.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>I've been seeing lockups with messages of this form:

(WW) AMDGPU(0): amdgpu_dri2_flip_event_handler: Pageflip completion event has
impossible msc XXXXXXX < target_msc YYYYYYY

After commenting this line, it seems to have gone away:

<a href="https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/blob/master/src/amdgpu_dri2.c#L494">https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/blob/master/src/amdgpu_dri2.c#L494</a>

That is, the messages are still logged, of course, but the lockups are gone
because the client is no longer signaling failure to the client. I haven't seen
any other adverse effects.

Should this be a warning only? One thing I noticed is the time is always 1 less
than expected:

[ 20308.275] (WW) AMDGPU(0): amdgpu_dri2_flip_event_handler: Pageflip
completion event has impossible msc 1868426 < target_msc 1868427
[716312.737] (WW) AMDGPU(0): amdgpu_dri2_flip_event_handler: Pageflip
completion event has impossible msc 43628303 < target_msc 43628304
[752121.770] (WW) AMDGPU(0): amdgpu_dri2_flip_event_handler: Pageflip
completion event has impossible msc 45776848 < target_msc 45776849
[833776.925] (WW) AMDGPU(0): amdgpu_dri2_flip_event_handler: Pageflip
completion event has impossible msc 50676148 < target_msc 50676149

Perhaps there is an off by one error somewhere? Also I believe, but can't
recall for sure sure, this problem only started once I enabled the TearFree
option in the driver.</pre>
        </div>
      </p>


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