3.10.2-031002-generic, ThinkPad X201 + External Display on Display Port
Internal Display always work, external display works intermittently (mostly on lower resolution) 

[ 1144.273801] ------------[ cut here ]------------
[ 1144.273850] WARNING: at /home/apw/COD/linux/drivers/gpu/drm/i915/intel_display.c:979 intel_wait_for_pipe_off+0x1bc/0x1d0 [i915]()
[ 1144.273853] pipe_off wait timed out
[ 1144.273855] Modules linked in: hidp pci_stub vboxpci(OF) vboxnetadp(OF) vboxnetflt(OF) vboxdrv(OF) zram(C) deflate ctr twofish_generic twofish_x86_64_3way twofish_x86_64 twofish_common camellia_generic camellia_x86_64 serpent_sse2_x86_64 xts serpent_generic blowfish_generic blowfish_x86_64 blowfish_common cast5_generic cast_common des_generic cmac xcbc rmd160 crypto_null af_key xfrm_algo dm_crypt parport_pc ppdev rfcomm bnep nfsd usblp auth_rpcgss nfs_acl nfs lockd sunrpc binfmt_misc fscache arc4 iwldvm btusb mac80211 bluetooth joydev dm_multipath scsi_dh iwlwifi i915 snd_hda_codec_hdmi cfg80211 intel_powerclamp drm_kms_helper snd_hda_codec_conexant snd_hda_intel drm snd_hda_codec crc32_pclmul ghash_clmulni_intel psmouse aesni_intel mei_me aes_x86_64 lrw snd_hwdep mei gf128mul snd_pcm glue_helper serio_raw ablk_helper cryptd mac_hid i2c_algo_bit snd_page_alloc lpc_ich tpm_tis intel_ips wmi video sata_sil24 thinkpad_acpi nvram snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore i2c_intel_mid kvm_intel kvm intelfb coretemp lp parport ext2 zfs(POF) zunicode(POF) zavl(POF) zcommon(POF) znvpair(POF) spl(OF) zlib_deflate hid_generic usbhid hid ahci libahci e1000e ptp pps_core microcode
[ 1144.273966] CPU: 0 PID: 3390 Comm: Xorg Tainted: PF       WC O 3.10.2-031002-generic #201307212216
[ 1144.273969] Hardware name: LENOVO 3680N48/3680N48, BIOS 6QET70WW (1.40 ) 10/11/2012
[ 1144.273972]  ffffffffa067f818 ffff8801f85a39d8 ffffffff8170d37b ffff8801f85a3a18
[ 1144.273976]  ffffffff81059350 ffff8802301c4000 ffff88020e0bc000 0000000000071008
[ 1144.273980]  000000010003372f ffff8801f85a3fd8 0000000000000001 ffff8801f85a3a78
[ 1144.273984] Call Trace:
[ 1144.273997]  [<ffffffff8170d37b>] dump_stack+0x19/0x1b
[ 1144.274004]  [<ffffffff81059350>] warn_slowpath_common+0x70/0xa0
[ 1144.274007]  [<ffffffff81059436>] warn_slowpath_fmt+0x46/0x50
[ 1144.274030]  [<ffffffffa063c47c>] intel_wait_for_pipe_off+0x1bc/0x1d0 [i915]
[ 1144.274052]  [<ffffffffa063c59e>] intel_disable_pipe+0x10e/0x150 [i915]
[ 1144.274073]  [<ffffffffa063ceed>] ironlake_crtc_disable+0xbd/0x260 [i915]
[ 1144.274094]  [<ffffffffa063dba5>] __intel_set_mode+0x195/0x390 [i915]
[ 1144.274101]  [<ffffffff8135c3d4>] ? snprintf+0x34/0x40
[ 1144.274123]  [<ffffffffa0642826>] intel_set_mode+0x16/0x30 [i915]
[ 1144.274144]  [<ffffffffa0642aa5>] intel_crtc_set_config+0x265/0x330 [i915]
[ 1144.274165]  [<ffffffffa0504e1e>] drm_mode_set_config_internal+0x2e/0x60 [drm]
[ 1144.274181]  [<ffffffffa0507ad8>] drm_mode_setcrtc+0x2e8/0x540 [drm]
[ 1144.274201]  [<ffffffffa063339f>] ? intel_crtc_load_lut+0x8f/0xb0 [i915]
[ 1144.274215]  [<ffffffffa04f756a>] drm_ioctl+0x50a/0x650 [drm]
[ 1144.274231]  [<ffffffffa05077f0>] ? drm_mode_setplane+0x3e0/0x3e0 [drm]
[ 1144.274236]  [<ffffffff8109350c>] ? account_user_time+0x9c/0xb0
[ 1144.274241]  [<ffffffff811b29d8>] do_vfs_ioctl+0x88/0x340
[ 1144.274245]  [<ffffffff811b2d21>] SyS_ioctl+0x91/0xb0
[ 1144.274250]  [<ffffffff8172226f>] tracesys+0xe1/0xe6
[ 1144.274253] ---[ end trace 4bc8164d27a54c7e ]---