[ 6081.561170] ------------[ cut here ]------------
[ 6081.561188] WARNING: CPU: 1 PID: 721 at drivers/gpu/drm/i915/intel_dp.c:4587 intel_digital_port_connected+0x146/0x270 [i915]()
[ 6081.561189] Missing switch case (4) in cpt_digital_port_connected
[ 6081.561190] Modules linked in: ax88179_178a usbnet mii snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic i915 snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core x86_pkg_temp_thermal coretemp snd_pcm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel i2c_hid e1000e ptp pps_core
[ 6081.561200] CPU: 1 PID: 721 Comm: X Tainted: G        W       4.2.0-rc8-gfxbench+ #1
[ 6081.561201] Hardware name: System manufacturer System Product Name/Z170M-PLUS, BIOS 0408 08/28/2015
[ 6081.561202]  ffffffffa021e880 ffff8800a4e3fb08 ffffffff816fd15e 0000000000000001
[ 6081.561204]  ffff8800a4e3fb58 ffff8800a4e3fb48 ffffffff81071212 ffff8800a4e3fb78
[ 6081.561205]  ffff8800a4ee0000 0000000000800000 ffff880248499800 0000000000000012
[ 6081.561207] Call Trace:
[ 6081.561210]  [<ffffffff816fd15e>] dump_stack+0x4f/0x7b
[ 6081.561213]  [<ffffffff81071212>] warn_slowpath_common+0x92/0xd0
[ 6081.561214]  [<ffffffff810712f1>] warn_slowpath_fmt+0x41/0x50
[ 6081.561221]  [<ffffffffa01535ae>] ? skl_power_well_enable+0xe/0x10 [i915]
[ 6081.561232]  [<ffffffffa01d6a86>] intel_digital_port_connected+0x146/0x270 [i915]
[ 6081.561241]  [<ffffffffa01d73d8>] intel_dp_detect+0xc8/0x4c0 [i915]
[ 6081.561244]  [<ffffffff8147eb43>] drm_helper_probe_single_connector_modes_merge_bits+0x2e3/0x490
[ 6081.561245]  [<ffffffff814989b1>] ? _object_find+0x71/0xb0
[ 6081.561247]  [<ffffffff8147ed0e>] drm_helper_probe_single_connector_modes+0xe/0x10
[ 6081.561249]  [<ffffffff8149dc4f>] drm_mode_getconnector+0x33f/0x3a0
[ 6081.561251]  [<ffffffff8119b640>] ? __pollwait+0xf0/0xf0
[ 6081.561253]  [<ffffffff8148fec8>] drm_ioctl+0x2a8/0x4a0
[ 6081.561255]  [<ffffffff8149d910>] ? drm_mode_getcrtc+0x140/0x140
[ 6081.561256]  [<ffffffff811a4192>] ? __fget+0x72/0xa0
[ 6081.561257]  [<ffffffff8119a81e>] do_vfs_ioctl+0x7e/0x4f0
[ 6081.561258]  [<ffffffff811a4192>] ? __fget+0x72/0xa0
[ 6081.561260]  [<ffffffff8119acd7>] SyS_ioctl+0x47/0x80
[ 6081.561261]  [<ffffffff8170355b>] entry_SYSCALL_64_fastpath+0x16/0x6e
[ 6081.561262] ---[ end trace eeaf0fd2c8fed65d ]---
[ 6279.653601] [drm:i915_hangcheck_elapsed [i915]] *ERROR* Hangcheck timer elapsed... render ring idle