Same issue here with a Dell Latitude
[157658.178997] ------------[ cut here ]------------
[157658.179095] WARNING: CPU: 2 PID: 1869 at /build/buildd/linux-3.16.0/drivers/gpu/drm/i915/intel_display.c:3324 intel_crtc_wait_for_pending_flips+0x16c/0x180 [i915]()
[157658.179100] Modules linked in: nls_utf8 btrfs xor raid6_pq ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs libcrc32c xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_codec_generic pci_stub vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) bnep rfcomm bluetooth 6lowpan_iphc dell_wmi sparse_keymap intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel arc4 dell_laptop dcdbas uvcvideo iwldvm videobuf2_vmalloc mac80211 binfmt_misc videobuf2_memops aesni_intel aes_x86_64 lrw videobuf2_core gf128mul v4l2_common glue_helper videodev ablk_helper
[157658.179197]  cryptd media joydev serio_raw iwlwifi cfg80211 wmi dell_smo8800 snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_seq_midi_event i915 snd_rawmidi snd_seq snd_seq_device snd_timer video mac_hid drm_kms_helper lpc_ich drm snd mei_me soundcore mei shpchp i2c_algo_bit parport_pc ppdev lp parport hid_generic usbhid hid firewire_ohci sdhci_pci e1000e sdhci psmouse firewire_core ahci ptp libahci crc_itu_t pps_core
[157658.179272] CPU: 2 PID: 1869 Comm: Xorg Tainted: G        W  OE 3.16.0-23-generic #31-Ubuntu
[157658.179277] Hardware name: Dell Inc. Latitude E6520/0CMN08, BIOS A19 11/14/2013
[157658.179282]  0000000000000009 ffff880035f47bf8 ffffffff8177fcbc 0000000000000000
[157658.179289]  ffff880035f47c30 ffffffff8106fd8d 0000000000000000 ffff8800c328a000
[157658.179296]  ffff880035cb8210 ffff8801277a4800 ffff8801277a4800 ffff880035f47c40
[157658.179303] Call Trace:
[157658.179320]  [<ffffffff8177fcbc>] dump_stack+0x45/0x56
[157658.179332]  [<ffffffff8106fd8d>] warn_slowpath_common+0x7d/0xa0
[157658.179340]  [<ffffffff8106fe6a>] warn_slowpath_null+0x1a/0x20
[157658.179389]  [<ffffffffc02dcffc>] intel_crtc_wait_for_pending_flips+0x16c/0x180 [i915]
[157658.179402]  [<ffffffff810b9590>] ? prepare_to_wait_event+0x100/0x100
[157658.179448]  [<ffffffffc02dfac3>] intel_crtc_disable_planes+0x33/0x1c0 [i915]
[157658.179490]  [<ffffffffc02e0090>] ironlake_crtc_disable+0x50/0x980 [i915]
[157658.179538]  [<ffffffffc0201f53>] ? drm_modeset_lock+0x33/0xf0 [drm]
[157658.179546]  [<ffffffff81785ab2>] ? mutex_lock+0x12/0x30
[157658.179589]  [<ffffffffc02e1457>] intel_crtc_update_dpms+0x67/0xa0 [i915]
[157658.179630]  [<ffffffffc02e5ac9>] intel_connector_dpms+0x59/0x70 [i915]
[157658.179668]  [<ffffffffc01f8e19>] drm_mode_obj_set_property_ioctl+0x399/0x3a0 [drm]
[157658.179701]  [<ffffffffc01f8e50>] drm_mode_connector_property_set_ioctl+0x30/0x40 [drm]
[157658.179725]  [<ffffffffc01e7a4f>] drm_ioctl+0x1df/0x680 [drm]
[157658.179740]  [<ffffffff810a9de8>] ? __enqueue_entity+0x78/0x80
[157658.179750]  [<ffffffff8101e04f>] ? __switch_to_xtra+0x13f/0x170
[157658.179758]  [<ffffffff811f4bc8>] do_vfs_ioctl+0x2c8/0x4a0
[157658.179765]  [<ffffffff8178294d>] ? __schedule+0x39d/0x890
[157658.179771]  [<ffffffff811f4e21>] SyS_ioctl+0x81/0xa0
[157658.179779]  [<ffffffff81787ced>] system_call_fastpath+0x1a/0x1f
[157658.179784] ---[ end trace 615210e0689c33af ]---