Comment 46 for bug 1645056

The above are logs of my system booting with 4.4.0-75-generic. And the kern.log shows something related to drm on skylake:

   1 May 16 08:26:41 mtlb kernel: [238539.431888] ------------[ cut here ]------------
   2 May 16 08:26:41 mtlb kernel: [238539.431974] WARNING: CPU: 0 PID: 2319 at /build/linux-Hlembm/linux-4.4.0/ubuntu/i915/intel_pm.c:3675 skl_update_other_pipe_wm+0x16c/0x180 [i915_bpo]()
   3 May 16 08:26:41 mtlb kernel: [238539.431980] WARN_ON(!wm_changed)
   4 May 16 08:26:41 mtlb kernel: [238539.431984] Modules linked in: vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) nf_conntrack_netlink nfnetlink btrfs xor raid6_pq ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs libcrc32c cpuid hid_generic usbhid drbg ansi_cprng ctr ccm scsi_transport_iscsi veth pci_stub xfrm_user xfrm_algo xt_addrtype xt_conntrack br_netfilter rfcomm aufs ip6table_filter ip6_ tables xt_CHECKSUM iptable_mangle xt_tcpudp ipt_MASQUERADE nf_nat_masquerade_ipv4 xt_comment iptable_nat nf_conntrack_ipv4 snd_hrtimer nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc ip table_filter ip_tables x_tables bnep binfmt_misc zfs(PO) zunicode(PO) zcommon(PO) znvpair(PO) spl(O) zavl(PO) r8712u(CE) joydev hid_multitouch arc4 i2c_designware_platform i2c_designware_core asus_nb _wmi asus_wmi snd_soc_skl sparse_keymap snd_hda_codec_hdmi snd_soc_skl_ipc snd_hda_ext_core snd_hda_codec_conexant snd_soc_sst_ipc snd_hda_codec_generic snd_soc_sst_dsp snd_soc_core snd_compress ac97 _bus snd_pcm_dmaengine dw_dmac_core snd_hda_intel snd_hda_codec snd_hda_core iwlmvm uvcvideo videobuf2_vmalloc snd_hwdep mac80211 videobuf2_memops snd_pcm videobuf2_v4l2 videobuf2_core v4l2_common sn d_seq_midi snd_seq_midi_event videodev snd_rawmidi media snd_seq intel_rapl x86_pkg_temp_thermal intel_powerclamp btusb snd_seq_device coretemp btrtl iwlwifi snd_timer crct10dif_pclmul crc32_pclmul g hash_clmulni_intel cfg80211 aesni_intel aes_x86_64 lrw gf128mul snd glue_helper ablk_helper cryptd input_leds soundcore serio_raw processor_thermal_device mei_me intel_soc_dts_iosf idma64 shpchp mei virt_dma intel_lpss_pci hci_uart int3403_thermal btbcm btqca btintel bluetooth int3402_thermal int3400_thermal intel_lpss_acpi intel_lpss tpm_crb int340x_thermal_zone acpi_thermal_rel acpi_pad mac_hi d kvm_intel kvm irqbypass parport_pc ppdev sunrpc lp parport autofs4 i915_bpo intel_ips i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ahci drm libahci wmi i2c_hid hid pinc trl_sunrisepoint pinctrl_intel video fjes [last unloaded: vboxdrv]
   5 May 16 08:26:41 mtlb kernel: [238539.432322] CPU: 0 PID: 2319 Comm: Xorg Tainted: P WC OE 4.4.0-75-generic #96-Ubuntu
   6 May 16 08:26:41 mtlb kernel: [238539.432327] Hardware name: ASUSTeK COMPUTER INC. UX360CA/UX360CA, BIOS UX360CA.202 02/17/2016
   7 May 16 08:26:41 mtlb kernel: [238539.432333] 0000000000000286 00000000a255aaa5 ffff880078737920 ffffffff813f8493
   8 May 16 08:26:41 mtlb kernel: [238539.432343] ffff880078737968 ffffffffc0246b58 ffff880078737958 ffffffff81081302
   9 May 16 08:26:41 mtlb kernel: [238539.432352] ffff88016a432000 ffff88016a44a148 ffff88016a433000 ffff88016e12c378
  10 May 16 08:26:41 mtlb kernel: [238539.432360] Call Trace:
  11 May 16 08:26:41 mtlb kernel: [238539.432377] [<ffffffff813f8493>] dump_stack+0x63/0x90
  12 May 16 08:26:41 mtlb kernel: [238539.432391] [<ffffffff81081302>] warn_slowpath_common+0x82/0xc0
  13 May 16 08:26:41 mtlb kernel: [238539.432401] [<ffffffff8108139c>] warn_slowpath_fmt+0x5c/0x80
  14 May 16 08:26:41 mtlb kernel: [238539.432462] [<ffffffffc0167fec>] skl_update_other_pipe_wm+0x16c/0x180 [i915_bpo]
  15 May 16 08:26:41 mtlb kernel: [238539.432522] [<ffffffffc0168185>] skl_update_wm+0x185/0x610 [i915_bpo]
  16 May 16 08:26:41 mtlb kernel: [238539.432613] [<ffffffffc01f942f>] ? intel_ddi_enable_transcoder_func+0x17f/0x260 [i915_bpo]
  17 May 16 08:26:41 mtlb kernel: [238539.432672] [<ffffffffc016bf0e>] intel_update_watermarks+0x1e/0x30 [i915_bpo]
  18 May 16 08:26:41 mtlb kernel: [238539.432761] [<ffffffffc01db701>] haswell_crtc_enable+0x761/0x8e0 [i915_bpo]
  19 May 16 08:26:41 mtlb kernel: [238539.432850] [<ffffffffc01d7606>] intel_atomic_commit+0x5d6/0x14a0 [i915_bpo]
  20 May 16 08:26:41 mtlb kernel: [238539.432916] [<ffffffffc00c9bfe>] ? drm_atomic_check_only+0x18e/0x590 [drm]
  21 May 16 08:26:41 mtlb kernel: [238539.432972] [<ffffffffc00ca037>] drm_atomic_commit+0x37/0x60 [drm]
  22 May 16 08:26:41 mtlb kernel: [238539.433003] [<ffffffffc0119dc6>] drm_atomic_helper_set_config+0x76/0xb0 [drm_kms_helper]
  23 May 16 08:26:41 mtlb kernel: [238539.433051] [<ffffffffc00b8e12>] drm_mode_set_config_internal+0x62/0x100 [drm]
  24 May 16 08:26:41 mtlb kernel: [238539.433100] [<ffffffffc00bd46c>] drm_mode_setcrtc+0x3cc/0x4f0 [drm]
  25 May 16 08:26:41 mtlb kernel: [238539.433136] [<ffffffffc00ae722>] drm_ioctl+0x152/0x540 [drm]
  26 May 16 08:26:41 mtlb kernel: [238539.433184] [<ffffffffc00bd0a0>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
  27 May 16 08:26:41 mtlb kernel: [238539.433197] [<ffffffff81222c6f>] do_vfs_ioctl+0x29f/0x490
  28 May 16 08:26:41 mtlb kernel: [238539.433207] [<ffffffff8108e5a1>] ? __set_task_blocked+0x41/0xa0
  29 May 16 08:26:41 mtlb kernel: [238539.433218] [<ffffffff81090f36>] ? __set_current_blocked+0x36/0x60
  30 May 16 08:26:41 mtlb kernel: [238539.433226] [<ffffffff81222ed9>] SyS_ioctl+0x79/0x90
  31 May 16 08:26:41 mtlb kernel: [238539.433236] [<ffffffff810911ee>] ? SyS_rt_sigprocmask+0x8e/0xc0
  32 May 16 08:26:41 mtlb kernel: [238539.433249] [<ffffffff8183b972>] entry_SYSCALL_64_fastpath+0x16/0x71
  33 May 16 08:26:41 mtlb kernel: [238539.433256] ---[ end trace de268f92ce210bd7 ]---