Additional info:
reporter:       libreport-2.2.3
WARNING: CPU: 1 PID: 895 at drivers/gpu/drm/i915/intel_dp.c:3122 intel_dp_link_down+0x1a3/0x210 [i915]()
Modules linked in: fuse binfmt_misc xt_pkttype xt_LOG xt_multiport xt_conntrack iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack arc4 pn544_mei mei_phy pn544 hci nfc iTCO_wdt iTCO_vendor_support dell_wmi sparse_keymap ppdev dell_laptop dcdbas snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal coretemp kvm_intel snd_hda_codec_hdmi kvm crct10dif_pclmul crc32_pclmul iwlmvm crc32c_intel mac80211 ghash_clmulni_intel microcode joydev serio_raw btusb iwlwifi snd_hda_intel bluetooth uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core snd_hda_controller v4l2_common i2c_i801 videodev snd_hda_codec cfg80211 media snd_hwdep lpc_ich snd_seq mfd_core snd_seq_device rfkill snd_pcm sdhci_pci snd_timer shpchp snd mei_me mei soundcore tpm_tis tpm wmi parport_pc parport i2c_hid dell_smo8800 i2c_designware_platform dw_dmac dw_dmac_core i2c_designware_core i915 i2c_algo_bit drm_kms_helper e1000e drm ptp pps_core i2c_core sdhci_acpi sdhci mmc_core video
CPU: 1 PID: 895 Comm: X Not tainted 3.16.6-200.fc20.x86_64 #1
Hardware name: Dell Inc. Latitude E7440/091TRH, BIOS A08 02/18/2014
 0000000000000000 00000000a5861276 ffff88020a77b780 ffffffff81707d45
 0000000000000000 ffff88020a77b7b8 ffffffff8108d0bd ffff8800d9fe0000
 ffff880212e14800 0000000080000006 0000000000000002 ffff8800369480d8
Call Trace:
 [<ffffffff81707d45>] dump_stack+0x45/0x56
 [<ffffffff8108d0bd>] warn_slowpath_common+0x7d/0xa0
 [<ffffffff8108d1ea>] warn_slowpath_null+0x1a/0x20
 [<ffffffffa01718a3>] intel_dp_link_down+0x1a3/0x210 [i915]
 [<ffffffffa0176cf5>] intel_dp_complete_link_train+0x105/0x360 [i915]
 [<ffffffffa016ee87>] intel_ddi_pre_enable+0x127/0x1a0 [i915]
 [<ffffffffa0156b4f>] haswell_crtc_enable+0x3af/0xa30 [i915]
 [<ffffffffa01594f2>] __intel_set_mode+0x812/0x1590 [i915]
 [<ffffffffa015c926>] intel_set_mode+0x16/0x30 [i915]
 [<ffffffffa015d89d>] intel_crtc_set_config+0x8ed/0xdb0 [i915]
 [<ffffffffa006a6a1>] drm_mode_set_config_internal+0x61/0xe0 [drm]
 [<ffffffffa00a7ca3>] restore_fbdev_mode+0xb3/0xe0 [drm_kms_helper]
 [<ffffffffa00a7cf3>] drm_fb_helper_restore_fbdev_mode_unlocked+0x23/0x40 [drm_kms_helper]
 [<ffffffffa00a9928>] drm_fb_helper_set_par+0x28/0x70 [drm_kms_helper]
 [<ffffffff813cf097>] fb_set_var+0x197/0x440
 [<ffffffff811eadf1>] ? mem_cgroup_bad_page_check+0x21/0x30
 [<ffffffff81184ceb>] ? free_pages_prepare+0xab/0x1b0
 [<ffffffff811863a6>] ? free_hot_cold_page_list+0x46/0xa0
 [<ffffffff813c5791>] fbcon_blank+0x1f1/0x2f0
 [<ffffffff81446478>] do_unblank_screen+0xb8/0x1f0
 [<ffffffff8143d48e>] vt_ioctl+0x110e/0x1190
 [<ffffffff81430e79>] tty_ioctl+0x289/0xb70
 [<ffffffff812f1b89>] ? avc_has_perm+0xd9/0x1a0
 [<ffffffff81206c20>] do_vfs_ioctl+0x2e0/0x4a0
 [<ffffffff811f58ae>] ? ____fput+0xe/0x10
 [<ffffffff81206e61>] SyS_ioctl+0x81/0xa0
 [<ffffffff8170f3a9>] system_call_fastpath+0x16/0x1b