<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 - Unclaimed register detected before writing to register 0x20a8"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=92740">92740</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Unclaimed register detected before writing to register 0x20a8
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </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>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>andrew@lunn.ch
          </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>Similar, but different to <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [i915] kernel warning hsw_unclaimed_reg_debug intel_uncore.c:619"
   href="show_bug.cgi?id=91960">https://bugs.freedesktop.org/show_bug.cgi?id=91960</a>

Hardware is an Intel NUC5i3.

When i start mplayer to play a video file i get a kernel warning:

[  744.158990] WARNING: CPU: 2 PID: 973 at
drivers/gpu/drm/i915/intel_uncore.c:620 hsw_unclaimed_reg_debug+0x65/0x80
[i915]()
[  744.158993] Unclaimed register detected before writing to register 0x20a8
[  744.158995] Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl nfs
lockd grace fscache sunrpc intel_rapl iosf_mbi x86_pkg_temp_thermal
intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul
sha256_ssse3 sha256_generic hmac arc4 iwlmvm drbg ansi_cprng joydev btusb
aesni_intel mac80211 btrtl aes_x86_64 btbcm btintel bluetooth lrw gf128mul
snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi iTCO_wdt
iTCO_vendor_support glue_helper iwlwifi psmouse evdev snd_hda_intel
snd_hda_codec snd_hda_core ablk_helper snd_hwdep serio_raw cryptd cfg80211
snd_soc_rt5640 snd_soc_rl6231 snd_soc_core snd_compress pcspkr snd_pcm rfkill
nuvoton_cir tpm_tis sg rc_core i915 snd_timer tpm snd soundcore battery
regmap_i2c drm_kms_helper drm mei_me mei snd_soc_sst_acpi video
i2c_designware_platform
[  744.159052]  processor dw_dmac dw_dmac_core i2c_algo_bit i2c_designware_core
i2c_i801 button lpc_ich shpchp mfd_core acpi_pad tun autofs4 ext4 crc16 mbcache
jbd2 hid_logitech_hidpp sd_mod hid_logitech_dj usbhid crc32c_intel ahci libahci
libata scsi_mod ehci_pci ehci_hcd e1000e ptp pps_core xhci_pci xhci_hcd usbcore
usb_common fan thermal sdhci_acpi sdhci mmc_core i2c_hid hid
[  744.159083] CPU: 2 PID: 973 Comm: Xorg Not tainted 4.3.0-rc7 #2
[  744.159085] Hardware name:
\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff
\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff\xffffffff/NUC5i3RYB,
BIOS RYBDWi35.86A.0130.2014.1203.1639 12/03/2014
[  744.159087]  ffffffffa05104d0 ffffffff812c0209 ffff8802135c7b18
ffffffff8106eb2d
[  744.159091]  ffff880214800000 ffff8802135c7b68 00000000000020a8
00000000000020a8
[  744.159094]  0000000000000046 ffffffff8106ebac ffffffffa0510498
0000000000000030
[  744.159098] Call Trace:
[  744.159104]  [<ffffffff812c0209>] ? dump_stack+0x40/0x57
[  744.159108]  [<ffffffff8106eb2d>] ? warn_slowpath_common+0x7d/0xb0
[  744.159111]  [<ffffffff8106ebac>] ? warn_slowpath_fmt+0x4c/0x50
[  744.159131]  [<ffffffffa0494055>] ? hsw_unclaimed_reg_debug+0x65/0x80 [i915]
[  744.159149]  [<ffffffffa0496dd8>] ? gen8_write32+0x58/0x1b0 [i915]
[  744.159168]  [<ffffffffa0489d86>] ? gen8_logical_ring_get_irq+0x86/0xc0
[i915]
[  744.159185]  [<ffffffffa047948a>] ? __i915_wait_request+0x45a/0x500 [i915]
[  744.159189]  [<ffffffff810a9bc0>] ? wake_atomic_t_function+0x60/0x60
[  744.159207]  [<ffffffffa0479680>] ?
i915_gem_object_wait_rendering__nonblocking+0x150/0x290 [i915]
[  744.159225]  [<ffffffffa047c9d4>] ? i915_gem_set_domain_ioctl+0x94/0x120
[i915]
[  744.159239]  [<ffffffffa0345130>] ? drm_ioctl+0x110/0x440 [drm]
[  744.159255]  [<ffffffffa047c940>] ?
i915_gem_object_set_to_gtt_domain+0x150/0x150 [i915]
[  744.159260]  [<ffffffff810cf597>] ? hrtimer_start_range_ns+0x1c7/0x3b0
[  744.159264]  [<ffffffff811c9f0f>] ? do_vfs_ioctl+0x28f/0x480
[  744.159268]  [<ffffffff814433cd>] ? __sys_recvmsg+0x5d/0x70
[  744.159271]  [<ffffffff811ca174>] ? SyS_ioctl+0x74/0x80
[  744.159275]  [<ffffffff8154d636>] ? entry_SYSCALL_64_fastpath+0x16/0x75
[  744.159277] ---[ end trace 1b4d8646c926b774 ]---

This is with 4.3.0-rc7 but i have also tried 4.2.5, debian 4.2.0, debian 4.1.0
and they all give a warning at the same time.

Warning happens every time. After the warning, mplayer falls back to software
decoding since vdpau fails. xbmc is worse, just a blank screen.</pre>
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