[drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in dpll_hw_state.wrpll

[Lacyc3]

Very strange symptom: most of time, system boots up normally, X starts and everything works as good as expected. But after 5 minutes or more maybe 1 hour, attached screens blinks for a moment, and warning shows up in dmesg:

[ 107.308723] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in dpll_hw_state.wrpll (expected 0xb01e0813, found 0x00000000)
[ 107.308726] ------------[ cut here ]------------
[ 107.308735] WARNING: CPU: 6 PID: 985 at /build/linux-jJX2Dm/linux-4.2.0/drivers/gpu/drm/i915/intel_display.c:12326 check_crtc_state+0x2c5/0x440 [i915]()
[ 107.308736] pipe state doesn't match!
[ 107.308736] Modules linked in: pci_stub vboxpci(OE) vboxnetadp(OE) binfmt_misc vboxnetflt(OE) vboxdrv(OE) nls_iso8859_1 eeepc_wmi asus_wmi sparse_keymap int
el_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp kvm_intel kvm snd_hda_codec_hdmi snd_hda_codec_realtek crct10dif_pclmul snd_hda_codec_generic crc32_pclm
ul ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd snd_hda_intel snd_hda_codec snd_hda_core input_leds snd_hwdep snd_pcm
 serio_raw snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd mei_me lpc_ich soundcore mei shpchp tpm_infineon acpi_pad mac_hid n
ct6775 hwmon_vid coretemp parport_pc ppdev lp parport autofs4 btrfs raid10 raid1 raid0 multipath linear raid456 async_raid6_recov async_memcpy async_pq async_x
or async_tx xor
[ 107.308763] raid6_pq hid_generic usbhid hid mxm_wmi i915 psmouse i2c_algo_bit drm_kms_helper e1000e ahci drm libahci ptp pps_core wmi video
[ 107.308771] CPU: 6 PID: 985 Comm: Xorg Tainted: G OE 4.2.0-18-generic #22-Ubuntu
[ 107.308771] Hardware name: ASUS All Series/Z97-PRO, BIOS 2012 09/30/2014
[ 107.308772] 0000000000000000 00000000022b77bf ffff880428df77c8 ffffffff817e8c09
[ 107.308774] 0000000000000000 ffff880428df7820 ffff880428df7808 ffffffff8107b3c6
[ 107.308775] ffff880428df7848 ffff880428df78b0 ffff88042779d000 0000000000000001
[ 107.308776] Call Trace:
[ 107.308781] [<ffffffff817e8c09>] dump_stack+0x45/0x57
[ 107.308784] [<ffffffff8107b3c6>] warn_slowpath_common+0x86/0xc0
[ 107.308785] [<ffffffff8107b455>] warn_slowpath_fmt+0x55/0x70
[ 107.308795] [<ffffffffc01e4af7>] ? intel_pipe_config_compare+0xa67/0xc60 [i915]
[ 107.308802] [<ffffffffc01e4fb5>] check_crtc_state+0x2c5/0x440 [i915]
[ 107.308812] [<ffffffffc01f8d6d>] intel_modeset_check_state+0x21d/0x6d0 [i915]
[ 107.308820] [<ffffffffc01f9f27>] intel_crtc_set_config+0x4c7/0x580 [i915]
[ 107.308829] [<ffffffffc0051ee5>] ? drm_mode_create+0x25/0x60 [drm]
[ 107.308835] [<ffffffffc004b4c6>] drm_mode_set_config_internal+0x66/0x100 [drm]
[ 107.308841] [<ffffffffc004fb29>] drm_mode_setcrtc+0x3e9/0x500 [drm]
[ 107.308845] [<ffffffffc0040495>] drm_ioctl+0x125/0x610 [drm]
[ 107.308847] [<ffffffff8123e696>] ? fsnotify+0x316/0x4a0
[ 107.308852] [<ffffffffc004f740>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
[ 107.308854] [<ffffffff812108a5>] do_vfs_ioctl+0x295/0x480
[ 107.308856] [<ffffffff81087f61>] ? __set_task_blocked+0x41/0xa0
[ 107.308857] [<ffffffff81210b09>] SyS_ioctl+0x79/0x90
[ 107.308859] [<ffffffff8108ab8e>] ? SyS_rt_sigprocmask+0x8e/0xc0
[ 107.308861] [<ffffffff817ef9f2>] entry_SYSCALL_64_fastpath+0x16/0x75
[ 107.308862] ---[ end trace f328298c6ade8794 ]---
[ 107.308907] [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in dpll_hw_state.wrpll (expected 0xb01e0813, found 0x00000000)
[ 107.308908] ------------[ cut here ]------------

At this time, nothing particularly worrisome happen.
More than one hour later, X crashes and restarts. This is worrisome, because it can cause unsaved data loss.

This bug introduced in 15.10 (linux 4.2). Everything was fine in 15.04 (linux 3.19).

Its more likely a kernel -> intel-drm bug than X. Kernel warning & error message occur in Gentoo too (linux 4.2 and 4.3). Everything fine in 4.0.

ProblemType: Crash
DistroRelease: Ubuntu 15.10
Package: xserver-xorg-core 2:1.17.2-1ubuntu9
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CrashCounter: 1
Date: Sun Nov 22 21:00:59 2015
DistUpgraded: Fresh install
DistroCodename: wily
DistroVariant: ubuntu
DkmsStatus: virtualbox, 5.0.4, 4.2.0-18-generic, x86_64: installed
ExecutablePath: /usr/bin/Xorg
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller [8086:0412] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:8534]
InstallationDate: Installed on 2015-10-16 (37 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20151016)
MachineType: ASUS All Series
ProcCmdline: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
ProcEnviron:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-18-generic.efi.signed root=UUID=a901d76d-efa4-4def-889b-df04f6d3504e ro quiet splash nomdmonddf nomdmonisw vt.handoff=7
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 ?? ()
 ?? () from /usr/lib/xorg/modules/drivers/intel_drv.so
 ?? () from /usr/lib/xorg/modules/drivers/intel_drv.so
 ?? () from /usr/lib/xorg/modules/drivers/intel_drv.so
 ?? () from /usr/lib/xorg/modules/drivers/intel_drv.so
Title: Xorg crashed with SIGABRT
UdevLog: Error: [Errno 2] Nincs ilyen fájl vagy könyvtár: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

dmi.bios.date: 09/30/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 2012
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z97-PRO
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2012:bd09/30/2014:svnASUS:pnAllSeries:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnZ97-PRO:rvrRev1.xx:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: All Series
dmi.product.version: System Version
dmi.sys.vendor: ASUS
version.compiz: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.2-1ubuntu4
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.2-1ubuntu4
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A
xserver.bootTime: Sun Nov 22 21:01:09 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.17.2-1ubuntu9

[Lacyc3 (lacyc3)]

Related to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1501260
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1501765