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      <base href="https://bugs.freedesktop.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - [BSW]The infomation read from RC6 status register is wrong"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=80703">80703</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>[BSW]The infomation read from RC6 status register is wrong
          </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>Created <span class=""><a href="attachment.cgi?id=101997" name="attach_101997" title="The infomation read from RC6 status register is wrong">attachment 101997</a> <a href="attachment.cgi?id=101997&action=edit" title="The infomation read from RC6 status register is wrong">[details]</a></span>
The infomation read from RC6 status register is wrong

==System Environment==
--------------------------
Regression: No. 
It's first time to run the test.

Non-working platforms: BYT

==kernel==
--------------------------
origin/drm-intel-nightly: 1087d4bf01e79523898c6c31615bf0c369e0039a(fails)
    drm-intel-nightly: 2014y-06m-25d-13h-11m-05s integration manifest
origin/drm-intel-next-queued: 91565c85b66db820f01894a971d39aaef60c4325(fails)
    drm/i915: Don't try to look up object for non-existent fb    
origin/drm-intel-fixes: 8525a235c96a548873c6c5644f50df32b31f04c6(fails)
    drm/i915: vlv_prepare_pll is only needed in case of non DSI interfaces

==Bug detailed description==
-----------------------------
[root@x-bsw01 tools]# ./intel_reg_read 0x130094
0x130094 : 0xA1

If run igt case pm_rc6_residency, the result shows below:
[root@x-bsw01 tests]# ./pm_rc6_residency
IGT-Version: 1.7-g67e29a3 (x86_64) (Linux: 3.16.0-rc2_kcloud_1305a9_20140630+
x86_64)
Test assertion failure function rc6_residency_check, file
pm_rc6_residency.c:146:
Last errno: 0, Success
Failed assertion: diff >= (SLEEP_DURATION - RC6_FUDGE)
GPU was not in RC6 long enough. Check that the GPU is as idle as possible(ie.
no X, running and running no other tests)
Subtest rc6-residency-check: FAIL
This machine doesn't support rc6pp
This machine doesn't support rc6p
This machine doesn't support rc6
The residency counter: 0.000000
Test requirement not met in function rc6_residency_counter, file
pm_rc6_residency.c:130:
Last errno: 0, Success
Test requirement: (flag_support == 0)
This machine didn't entry any RC6 state.
Subtest rc6-residency-counter: SKIP


if apply the attached patch, we can see below debugfs information: 
[root@x-bsw01 ~]# cat /sys/kernel/debug/dri/64/i915_drpc_info 
Video Turbo Mode: no 
Turbo enabled: yes 
HW control enabled: yes 
SW control enabled: no 
RC6 Enabled: yes 
Render Power Well: Down 
Media Power Well: Down 
Render RC6 residency since boot: 210147482 
Media RC6 residency since boot: 210147747 
Forcewake Render Count = 0 
Forcewake Media Count = 0</pre>
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