My solution was to re-select gdm as the display manager; not even de-select then re-select. Something was re-linked at that point but i have no idea what.

----- Reply message -----
From: "Daniel Elstner" <email address hidden>
To: <email address hidden>
Subject: [Bug 1492764] Re: [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in ips_enabled (expected 1, found 0)
Date: Wed, Oct 28, 2015 13:28


I had the same problem, also on a T440s. Initially Ubuntu GNOME 15.10 worked just fine -- until it didn't.
However, in a strange twist contrary to comment #21, I got it to work again by switching from lightdm *to* gdm.

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Title:
  [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in ips_enabled
  (expected 1, found 0)

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  System: Kubuntu 15.10

  Since kernel version 4.2 I have a few of this errors:

  Sep 06 16:16:35 benediktZ50-70 kernel: [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in ips_enabled (expected 1, found 0)
  Sep 06 16:16:35 benediktZ50-70 kernel: ------------[ cut here ]------------
  Sep 06 16:16:35 benediktZ50-70 kernel: WARNING: CPU: 0 PID: 187 at /build/linux-4dBub_/linux-4.2.0/drivers/gpu/drm/i915/intel_display.c:12324 check_crtc_state+0x2c5/0x440 [i915]()
  Sep 06 16:16:35 benediktZ50-70 kernel: pipe state doesn't match!
  Sep 06 16:16:35 benediktZ50-70 kernel: Modules linked in: rtsx_usb_sdmmc rtsx_usb i915 i2c_algo_bit drm_kms_helper psmouse ahci drm libahci r8169 mii sdhci_acpi video sdhci i2c_hid hid
  Sep 06 16:16:35 benediktZ50-70 kernel: CPU: 0 PID: 187 Comm: plymouthd Tainted: G        W       4.2.0-7-generic #7-Ubuntu
  Sep 06 16:16:35 benediktZ50-70 kernel: Hardware name: LENOVO 20354/Lancer 5A5, BIOS 9BCN91WW 07/21/2015
  Sep 06 16:16:35 benediktZ50-70 kernel:  ffffffffc023f1e8 ffff8802413277e8 ffffffff817b0465 0000000000000000
  Sep 06 16:16:35 benediktZ50-70 kernel:  ffff880241327838 ffff880241327828 ffffffff81076536 ffff880241327858
  Sep 06 16:16:35 benediktZ50-70 kernel:  ffff8802413278c0 ffff880241152000 0000000000000001 ffff880241152350
  Sep 06 16:16:35 benediktZ50-70 kernel: Call Trace:
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff817b0465>] dump_stack+0x45/0x57
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff81076536>] warn_slowpath_common+0x86/0xc0
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff810765b6>] warn_slowpath_fmt+0x46/0x50
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc01d3091>] ? intel_pipe_config_compare+0xb31/0xc60 [i915]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc01d3485>] check_crtc_state+0x2c5/0x440 [i915]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc01e6f3e>] intel_modeset_check_state+0x20e/0x6b0 [i915]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc01e80e7>] intel_crtc_set_config+0x4c7/0x580 [i915]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc009f915>] ? drm_mode_create+0x25/0x60 [drm]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc0099036>] drm_mode_set_config_internal+0x66/0x100 [drm]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc009d5f8>] drm_mode_setcrtc+0x3a8/0x4c0 [drm]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc008e365>] drm_ioctl+0x125/0x610 [drm]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffffc009d250>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff811fffd5>] do_vfs_ioctl+0x285/0x470
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff811ac159>] ? do_munmap+0x349/0x480
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff81200239>] SyS_ioctl+0x79/0x90
  Sep 06 16:16:35 benediktZ50-70 kernel:  [<ffffffff817b6cf2>] entry_SYSCALL_64_fastpath+0x16/0x75
  Sep 06 16:16:35 benediktZ50-70 kernel: ---[ end trace 724377a3c01e4270 ]---


  I will check next week if these errors have any impact on my system.

  This is a Nvidia Optimus System with the Intel graphic card activated
  by default.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-4.2.0-7-generic 4.2.0-7.7
  ProcVersionSignature: Ubuntu 4.2.0-7.7-generic 4.2.0
  Uname: Linux 4.2.0-7-generic x86_64
  ApportVersion: 2.18-0ubuntu9
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  benedikt   1550 F.... pulseaudio
   /dev/snd/controlC1:  benedikt   1550 F.... pulseaudio
  CurrentDesktop: KDE
  Date: Sun Sep  6 16:22:48 2015
  HibernationDevice: UUID=3383b02e-b89c-462c-903a-cb936e81b2bf
  InstallationDate: Installed on 2014-12-21 (259 days ago)
  InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20141218)
  MachineType: LENOVO 20354
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-7-generic root=UUID=b549945a-67ac-4d14-849c-b54e561d47cc ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-7-generic N/A
   linux-backports-modules-4.2.0-7-generic  N/A
   linux-firmware                           1.147
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/21/2015
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 9BCN91WW
  dmi.board.asset.tag: No Asset Tag
  dmi.board.name: Lancer 5A5
  dmi.board.vendor: LENOVO
  dmi.board.version: 31900058WIN
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Lenovo Z50-70
  dmi.modalias: dmi:bvnLENOVO:bvr9BCN91WW:bd07/21/2015:svnLENOVO:pn20354:pvrLenovoZ50-70:rvnLENOVO:rnLancer5A5:rvr31900058WIN:cvnLENOVO:ct10:cvrLenovoZ50-70:
  dmi.product.name: 20354
  dmi.product.version: Lenovo Z50-70
  dmi.sys.vendor: LENOVO

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