Hi, I am also plagued by this very annoying bug.

I am running Ubuntu 16.04

kernel 4.3.0-7-generic #18-Ubuntu SMP Tue Jan 19 15:46:45 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

on a Dell XPS 13 9343

This particular laptop has a mini DisplayPort output which I connected to a DisplayPort MST hub. The DisplayPort outputs from this hub are connected with DP to HDMI cables to 3 full HD monitors. 

My dmesg shows lots of: [drm:gen8_irq_handler [i915]] *ERROR* The master control interrupt lied (SDE)!

I also see in the kernel log:

[   92.948779] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2] has bogus alignment
[   93.451068] ACPI Error: Cannot release Mutex [PATM], not acquired (20150818/exmutex-376)
[   93.451073] ACPI Error: Method parse/execution failed [\_SB.PCI0.LPCB.ECDV._Q66] (Node ffff8802170cae10), AE_AML_MUTEX_NOT_ACQUIRED (20150818/psparse-542)
[  288.672984] ------------[ cut here ]------------
[  288.673012] WARNING: CPU: 3 PID: 1278 at /build/linux-HskGKW/linux-4.3.0/drivers/gpu/drm/i915/intel_uncore.c:620 hsw_unclaimed_reg_debug+0x69/0x90 [i915]()
[  288.673014] Unclaimed register detected before writing to register 0x44414
[  288.673015] Modules linked in: rfcomm xt_addrtype xt_conntrack ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 iptable_filter ip_tables x_tables nf_nat nf_conntrack bridge stp llc pci_stub vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) aufs vboxdrv(OE) binfmt_misc bnep btusb btrtl btbcm btintel bluetooth snd_usb_audio hid_generic snd_usbmidi_lib uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core v4l2_common videodev media hid_multitouch dell_wmi sparse_keymap dell_laptop dcdbas snd_hda_codec_hdmi intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul wl(POE) aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd input_leds joydev serio_raw dell_led intel_pch_thermal snd_hda_codec_realtek snd_hda_codec_generic
[  288.673057]  cfg80211 mei_me lpc_ich rtsx_pci_ms memstick mei shpchp snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_soc_ssm4567 elan_i2c soc_button_array int3403_thermal dw_dmac dw_dmac_core 8250_dw snd_soc_sst_acpi spi_pxa2xx_platform i2c_designware_platform i2c_designware_core int3402_thermal mac_hid tpm_crb processor_thermal_device int340x_thermal_zone acpi_als int3400_thermal acpi_pad intel_soc_dts_iosf acpi_thermal_rel kfifo_buf industrialio kvm_intel kvm snd_soc_rt286 snd_soc_rl6347a snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore parport_pc ppdev lp parport autofs4 btrfs xor hid_logitech_hidpp hid_logitech_dj raid6_pq usbhid rtsx_pci_sdmmc i915 i2c_algo_bit drm_kms_helper psmouse
[  288.673096]  syscopyarea sysfillrect sysimgblt fb_sys_fops ahci drm libahci rtsx_pci wmi video sdhci_acpi i2c_hid sdhci hid fjes
[  288.673108] CPU: 3 PID: 1278 Comm: Xorg Tainted: P           OE   4.3.0-7-generic #18-Ubuntu
[  288.673110] Hardware name: Dell Inc. XPS 13 9343/09K8G1, BIOS A07 11/11/2015
[  288.673112]  0000000000000000 0000000066689b11 ffff8800c2afbb70 ffffffff813d2674
[  288.673115]  ffff8800c2afbbb8 ffff8800c2afbba8 ffffffff8107d6e2 ffff880211600000
[  288.673117]  0000000000044414 0000000000044414 ffff880211600080 0000000000000046
[  288.673119] Call Trace:
[  288.673125]  [<ffffffff813d2674>] dump_stack+0x44/0x60
[  288.673128]  [<ffffffff8107d6e2>] warn_slowpath_common+0x82/0xc0
[  288.673130]  [<ffffffff8107d77c>] warn_slowpath_fmt+0x5c/0x80
[  288.673146]  [<ffffffffc01ddae9>] hsw_unclaimed_reg_debug+0x69/0x90 [i915]
[  288.673160]  [<ffffffffc01e0ada>] gen8_write32+0x5a/0x1b0 [i915]
[  288.673169]  [<ffffffffc018f32d>] gen8_enable_vblank+0x5d/0x90 [i915]
[  288.673180]  [<ffffffffc009b919>] drm_vblank_enable+0x79/0xd0 [drm]
[  288.673187]  [<ffffffffc009ba11>] drm_vblank_get+0xa1/0xd0 [drm]
[  288.673195]  [<ffffffffc009ccb0>] drm_wait_vblank+0x90/0x5c0 [drm]
[  288.673203]  [<ffffffffc009a538>] drm_ioctl+0x138/0x500 [drm]
[  288.673211]  [<ffffffffc009cc20>] ? drm_modeset_ctl+0x60/0x60 [drm]
[  288.673214]  [<ffffffff81215ea5>] do_vfs_ioctl+0x295/0x480
[  288.673217]  [<ffffffff81216109>] SyS_ioctl+0x79/0x90
[  288.673221]  [<ffffffff817fc572>] entry_SYSCALL_64_fastpath+0x16/0x71

As a consequence, my monitors randomly turn black and on again for about half a second to a full second. This happens in no particular order, sometimes only one is exhibiting this behavior, sometimes two at the same time, sometimes they do it a lot and at other times just once in a while. But when they start to flicker, I noticed it especially happens with the monitor that is currently focused. 

Now the really interesting thing I have noticed is that this only happens when my monitors are at the 1920 x 1080 resolution.  If I switch to 1280 x 1024, this never ever happens.

Hope this makes things a bit clearer for somebody out there.