Description of problem:
External monitor, which is plugged into the DisplayPort, went to sleep. Upon waking it I found the error.

Additional info:
reporter:       libreport-2.2.0
WARNING: CPU: 2 PID: 849 at drivers/gpu/drm/i915/intel_display.c:851 intel_wait_for_pipe_off+0x1db/0x1f0 [i915]()
pipe_off wait timed out
Modules linked in: rndis_host cdc_ether usbnet mii usb_storage tcp_lp rfcomm ipt_MASQUERADE xt_CHECKSUM tun fuse ip6t_rpfilter ip6t_REJECT xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables bnep iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw iTCO_wdt iTCO_vendor_support snd_hda_codec_hdmi mxm_wmi snd_hda_codec_conexant coretemp kvm_intel arc4 snd_hda_intel snd_hda_codec snd_hwdep kvm iwldvm mac80211 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core videodev snd_seq microcode snd_seq_device media joydev snd_pcm serio_raw iwlwifi intel_ips btusb sdhci_pci bluetooth i2c_i801 sdhci lpc_ich e1000e snd_page_alloc mfd_core cfg80211 snd_timer mmc_core mei_me mei ptp thinkpad_acpi shpchp snd pps_core soundcore rfkill wmi acpi_cpufreq nfsd auth_rpcgss nfs_acl lockd sunrpc binfmt_misc dm_crypt btrfs libcrc32c xor raid6_pq crct10dif_pclmul crc32_pclmul crc32c_intel i915 ghash_clmulni_intel firewire_ohci i2c_algo_bit drm_kms_helper firewire_core crc_itu_t drm i2c_core video loop
CPU: 2 PID: 849 Comm: Xorg Not tainted 3.13.6-200.fc20.x86_64 #1
Hardware name: LENOVO 2522BQ9/2522BQ9, BIOS 6IET85WW (1.45 ) 02/14/2013
 0000000000000009 ffff8802264e7bd0 ffffffff8168730c ffff8802264e7c18
 ffff8802264e7c08 ffffffff8106d47d ffff88022d744000 0000000000070008
 0000000102a82bc3 0000000000000000 ffff88022d877b20 ffff8802264e7c68
Call Trace:
 [<ffffffff8168730c>] dump_stack+0x45/0x56
 [<ffffffff8106d47d>] warn_slowpath_common+0x7d/0xa0
 [<ffffffff8106d4ec>] warn_slowpath_fmt+0x4c/0x50
 [<ffffffffa01309f8>] ? gen5_read32+0x48/0xc0 [i915]
 [<ffffffffa00f12cb>] intel_wait_for_pipe_off+0x1db/0x1f0 [i915]
 [<ffffffffa00f1380>] intel_disable_pipe+0xa0/0xb0 [i915]
 [<ffffffffa00f2454>] ironlake_crtc_disable+0xe4/0x940 [i915]
 [<ffffffff810925aa>] ? __hrtimer_start_range_ns+0x1ba/0x3e0
 [<ffffffffa00f8adf>] intel_crtc_update_dpms+0x6f/0xa0 [i915]
 [<ffffffffa00fc449>] intel_connector_dpms+0x59/0x70 [i915]
 [<ffffffffa003c3f8>] drm_mode_obj_set_property_ioctl+0x328/0x340 [drm]
 [<ffffffffa003c440>] drm_mode_connector_property_set_ioctl+0x30/0x40 [drm]
 [<ffffffffa002bb52>] drm_ioctl+0x502/0x630 [drm]
 [<ffffffff811cb758>] do_vfs_ioctl+0x2d8/0x4a0
 [<ffffffff810fc2a6>] ? __audit_syscall_exit+0x1f6/0x2a0
 [<ffffffff811cb9a1>] SyS_ioctl+0x81/0xa0
 [<ffffffff816962e9>] system_call_fastpath+0x16/0x1b