<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 - [BAT][HSW] Unclaimed read from register 0x[4c]400c"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=102543">102543</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[BAT][HSW] Unclaimed read from register 0x[4c]400c
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>XOrg git
          </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>martin.peres@free.fr
          </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>Starting from CI_DRM_3033, the machine shard-hsw produced the following warning
when running the test igt@tools_test@tools_test:

[  227.980159] Unclaimed read from register 0xc400c
[  227.980198] ------------[ cut here ]------------
[  227.980233] WARNING: CPU: 3 PID: 0 at
drivers/gpu/drm/i915/intel_uncore.c:792 __unclaimed_reg_debug+0x47/0x60 [i915]
[  227.980235] Modules linked in: vgem snd_hda_codec_hdmi i915
snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal
intel_powerclamp coretemp crct10dif_pclmul snd_hda_intel crc32_pclmul
snd_hda_codec snd_hwdep ghash_clmulni_intel snd_hda_core r8169 snd_pcm mii
mei_me mei prime_numbers lpc_ich
[  227.980271] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G     U         
4.13.0-CI-CI_DRM_3037+ #1
[  227.980273] Hardware name: MSI MS-7924/Z97M-G43(MS-7924), BIOS V1.12
02/15/2016
[  227.980275] task: ffff88040d562800 task.stack: ffffc9000009c000
[  227.980300] RIP: 0010:__unclaimed_reg_debug+0x47/0x60 [i915]
[  227.980302] RSP: 0018:ffff88041fac3e28 EFLAGS: 00010092
[  227.980306] RAX: 0000000000000024 RBX: 0000000000000000 RCX:
0000000000010003
[  227.980308] RDX: 0000000080010003 RSI: ffffffff81d021bf RDI:
00000000ffffffff
[  227.980309] RBP: ffff88041fac3e40 R08: 0000000000000000 R09:
0000000000000001
[  227.980311] R10: ffff88041fac3db8 R11: 00000000fa823003 R12:
00000000000c400c
[  227.980313] R13: 0000000000000001 R14: 00000000ffffffff R15:
ffff8803fa380ba8
[  227.980315] FS:  0000000000000000(0000) GS:ffff88041fac0000(0000)
knlGS:0000000000000000
[  227.980316] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  227.980318] CR2: 00007f5255477788 CR3: 0000000003e0f000 CR4:
00000000001406e0
[  227.980320] Call Trace:
[  227.980322]  <IRQ>
[  227.980347]  gen6_read32+0x22d/0x2b0 [i915]
[  227.980367]  ironlake_irq_handler+0xac/0xa80 [i915]
[  227.980372]  __handle_irq_event_percpu+0x49/0x350
[  227.980376]  handle_irq_event_percpu+0x23/0x60
[  227.980379]  handle_irq_event+0x39/0x60
[  227.980382]  handle_edge_irq+0xf4/0x1c0
[  227.980385]  handle_irq+0x1a/0x30
[  227.980389]  do_IRQ+0x68/0x130
[  227.980392]  common_interrupt+0x90/0x90
[  227.980395] RIP: 0010:cpuidle_enter_state+0x136/0x370
[  227.980397] RSP: 0018:ffffc9000009fe80 EFLAGS: 00000212 ORIG_RAX:
ffffffffffffff8d
[  227.980400] RAX: ffff88040d562800 RBX: 0000000000020319 RCX:
0000000000000001
[  227.980402] RDX: 0000000000000000 RSI: ffffffff81cf77c4 RDI:
ffffffff81cae67e
[  227.980403] RBP: ffffc9000009feb8 R08: 0000000000000331 R09:
0000000000000018
[  227.980405] R10: 0000000000000000 R11: 0000000000000000 R12:
0000000000000005
[  227.980407] R13: 0000000000000005 R14: ffffe8ffffcc0530 R15:
0000003514aaa3ef
[  227.980408]  </IRQ>
[  227.980416]  cpuidle_enter+0x17/0x20
[  227.980419]  call_cpuidle+0x23/0x40
[  227.980422]  do_idle+0x192/0x1e0
[  227.980426]  cpu_startup_entry+0x1d/0x20
[  227.980430]  start_secondary+0x102/0x120
[  227.980434]  secondary_startup_64+0x9f/0x9f
[  227.980439] Code: 01 75 31 84 db 75 2d 45 84 ed 48 c7 c0 da 7b 44 a0 48 c7
c6 d0 7b 44 a0 48 0f 44 f0 44 89 e2 48 c7 c7 e3 7b 44 a0 e8 6a 4d d6 e0 <0f> ff
83 2d a4 ef 0f 00 01 5b 41 5c 41 5d 5d c3 66 0f 1f 84 00 
[  227.980527] ---[ end trace f0a9fad54483215d ]---

This happens 100% of the time, and it seems to have come due to one of this
commits: <a href="https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3033/commits_short.log">https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3033/commits_short.log</a>

Full logs:
<a href="https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3033/shard-hsw3/igt@tools_test@tools_test.html">https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3033/shard-hsw3/igt@tools_test@tools_test.html</a></pre>
        </div>
      </p>


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