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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 - rc6_residency_ms unreliable"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=94852">94852</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>rc6_residency_ms unreliable
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr>

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

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

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </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>lenb@kernel.org
          </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>Kernel: Linux-4.6.0-rc1

Hardware: SKL, HSW

Description:
Value read from /sys/class/drm/card0/power/rc6_residency_ms
resets before it reaches 5500 seconds.

This make it "somewhat awkward" to calculate residence from this counter,
since it can effectively go backwards - or worse, appear to increment
extremely slowly when it should really be incrementing quickly.

turbostat has a workaround for former, but there is no workaround
for the later.  powertop does not have a workaround, it will just
occasionally display garbage.

Debug steps taken:
booted both the SKL and HSW with cmdline "i915.enable_dc=0"
but it made no difference.

To Reproduce:
while /bin/true; do cat /sys/class/drm/card0/power/rc6_residency_ms; sleep 1;
done
...
5491367
5492352
5493334
5494326
5495307
5496299
5497280
703
1685
2677
3658
4650
5631
6612</pre>
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