I tested 

Linux linuxkiste 3.15.0-997-generic #201406070420 SMP Sat Jun 7 08:21:19 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

which has a newer driver version:

[drm] Initialized i915 1.6.0 20140606 for 0000:00:02.0 on minor 0

but it shows the same error upon resume:

[  171.201957] ------------[ cut here ]------------
[  171.201980] WARNING: CPU: 3 PID: 171 at /home/apw/COD/linux/drivers/gpu/drm/i915/intel_ddi.c:911 intel_ddi_pll_enable+0x23f/0x250 [i915]()
[  171.201980] SPLL already enabled
[  171.201996] Modules linked in: nls_iso8859_1 pci_stub vboxpci(OE) vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) bnep rfcomm bluetooth 6lowpan_iphc snd_hda_codec_realtek snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel x86_pkg_temp_thermal snd_hda_controller snd_hda_codec intel_powerclamp snd_hwdep snd_pcm coretemp snd_seq_midi kvm_intel kvm snd_seq_midi_event snd_rawmidi snd_seq parport_pc microcode ppdev lp shpchp parport intel_smartconnect snd_seq_device snd_timer mei_me mei snd lpc_ich mac_hid tpm_infineon serio_raw soundcore uas usb_storage dm_crypt hid_generic usbhid hid crct10dif_pclmul mxm_wmi crc32_pclmul ghash_clmulni_intel i915 aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd i2c_algo_bit drm_kms_helper ahci drm r8169 libahci mii wmi video
[  171.201997] CPU: 3 PID: 171 Comm: kworker/u8:3 Tainted: G           OE 3.15.0-997-generic #201406070420
[  171.201998] Hardware name: MSI MS-7817/CSM-B85M-E45 (MS-7817), BIOS V10.5 05/30/2014
[  171.202001] Workqueue: events_unbound async_run_entry_fn
[  171.202003]  000000000000038f ffff88020fb67a78 ffffffff81760e58 ffffffff81c51418
[  171.202003]  ffff88020fb67ac8 ffff88020fb67ab8 ffffffff810699cc ffff88020fb67ad8
[  171.202004]  0000000094000000 ffff88020f7f0000 0000000094000000 0000000000000001
[  171.202005] Call Trace:
[  171.202008]  [<ffffffff81760e58>] dump_stack+0x46/0x58
[  171.202010]  [<ffffffff810699cc>] warn_slowpath_common+0x8c/0xc0
[  171.202012]  [<ffffffff81069ab6>] warn_slowpath_fmt+0x46/0x50
[  171.202024]  [<ffffffffa0177d2f>] intel_ddi_pll_enable+0x23f/0x250 [i915]
[  171.202034]  [<ffffffffa012fc10>] ? is_pin_display+0x30/0x60 [i915]
[  171.202044]  [<ffffffffa0154a37>] haswell_crtc_mode_set+0x27/0x40 [i915]
[  171.202055]  [<ffffffffa0165772>] __intel_set_mode+0x262/0x420 [i915]
[  171.202065]  [<ffffffffa0168597>] intel_modeset_setup_hw_state+0x357/0x3c0 [i915]
[  171.202067]  [<ffffffff813bd3a0>] ? pci_pm_suspend_noirq+0x1a0/0x1a0
[  171.202073]  [<ffffffffa0106d20>] __i915_drm_thaw+0x130/0x1b0 [i915]
[  171.202080]  [<ffffffffa01077c8>] i915_resume+0x28/0x50 [i915]
[  171.202082]  [<ffffffff813bd3a0>] ? pci_pm_suspend_noirq+0x1a0/0x1a0
[  171.202087]  [<ffffffffa0107806>] i915_pm_resume+0x16/0x20 [i915]
[  171.202089]  [<ffffffff813bd433>] pci_pm_restore+0x93/0xf0
[  171.202091]  [<ffffffff814b7096>] dpm_run_callback+0x56/0xa0
[  171.202092]  [<ffffffff814b799e>] device_resume+0xde/0x210
[  171.202093]  [<ffffffff814b7af1>] async_resume+0x21/0x50
[  171.202094]  [<ffffffff810941fb>] async_run_entry_fn+0x3b/0x140
[  171.202096]  [<ffffffff81085e3f>] process_one_work+0x17f/0x4c0
[  171.202097]  [<ffffffff81086d8b>] worker_thread+0x11b/0x3d0
[  171.202098]  [<ffffffff81086c70>] ? manage_workers.isra.21+0x190/0x190
[  171.202099]  [<ffffffff8108de79>] kthread+0xc9/0xe0
[  171.202100]  [<ffffffff8108ddb0>] ? flush_kthread_worker+0xb0/0xb0
[  171.202102]  [<ffffffff817771bc>] ret_from_fork+0x7c/0xb0
[  171.202102]  [<ffffffff8108ddb0>] ? flush_kthread_worker+0xb0/0xb0
[  171.202103] ---[ end trace b7f4aac5ddf9c48a ]---

Attached are the dmesg output during a normal boot and the one during a hibernation resume boot, both with "drm.debug=0xe".