[    3.797565] WARNING: CPU: 0 PID: 374 at drivers/gpu/drm/i915/intel_display.c:1785 vlv_wait_port_ready+0xa8/0xe0
[    3.797567] timed out waiting for port C ready: got 0x20, expected 0xe0
[    3.797571] CPU: 0 PID: 374 Comm: kworker/u4:3 Not tainted 4.9.0-rc1+ #1
[    3.797573] Hardware name: Dell Inc. Inspiron 14-3452/0HHRWV, BIOS 4.0.11 08/24/2016
[    3.797580] Workqueue: events_unbound async_run_entry_fn
[    3.797587]  ffffc900006876f0 ffffffff81300e2a ffffc90000687740 0000000000000000
[    3.797591]  ffffc90000687730 ffffffff81091b7b 000006f98149b63e ffff880275db0000
[    3.797594]  0000000000186014 00000000000000e0 ffff880276bb8000 00000000000000f0
[    3.797595] Call Trace:
[    3.797602]  [<ffffffff81300e2a>] dump_stack+0x4d/0x63
[    3.797606]  [<ffffffff81091b7b>] __warn+0xcb/0xf0
[    3.797608]  [<ffffffff81091bec>] warn_slowpath_fmt+0x4c/0x50
[    3.797611]  [<ffffffff814b79c8>] vlv_wait_port_ready+0xa8/0xe0
[    3.797617]  [<ffffffff814e7f80>] intel_enable_dp+0x120/0x290
[    3.797619]  [<ffffffff814e816d>] chv_pre_enable_dp+0x1d/0x30
[    3.797623]  [<ffffffff814ab894>] intel_encoders_pre_enable.isra.38+0x64/0x80
[    3.797628]  [<ffffffff814be774>] valleyview_crtc_enable+0xf4/0x210
[    3.797631]  [<ffffffff814bafb7>] intel_update_crtc+0x57/0x100
[    3.797634]  [<ffffffff814bb0c6>] intel_update_crtcs+0x66/0x80
[    3.797637]  [<ffffffff814bb823>] intel_atomic_commit_tail+0x373/0x1080
[    3.797646]  [<ffffffff814188f6>] ? drm_atomic_helper_prepare_planes+0x76/0x140
[    3.797651]  [<ffffffff81419287>] ? drm_atomic_helper_swap_state+0x117/0x2e0
[    3.797655]  [<ffffffff814bc9ae>] intel_atomic_commit+0x47e/0x5b0
[    3.797661]  [<ffffffff814387c7>] ? drm_atomic_add_affected_connectors+0x57/0xe0
[    3.797664]  [<ffffffff81439036>] drm_atomic_commit+0x46/0x50
[    3.797666]  [<ffffffff8141c896>] restore_fbdev_mode+0x156/0x280
[    3.797671]  [<ffffffff8141f3be>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2e/0x80
[    3.797673]  [<ffffffff8141f438>] drm_fb_helper_set_par+0x28/0x60
[    3.797679]  [<ffffffff814d6fe3>] intel_fbdev_set_par+0x13/0x70
[    3.797683]  [<ffffffff8136d955>] fbcon_init+0x535/0x5a0
[    3.797688]  [<ffffffff813dea79>] visual_init+0xa9/0x100
[    3.797690]  [<ffffffff813e093a>] do_bind_con_driver+0x11a/0x330
[    3.797693]  [<ffffffff813e1650>] do_take_over_console+0xf0/0x160
[    3.797695]  [<ffffffff813694f2>] do_fbcon_takeover+0x52/0xb0
[    3.797698]  [<ffffffff8136e4df>] fbcon_event_notify+0x75f/0x870
[    3.797701]  [<ffffffff810b0337>] notifier_call_chain+0x47/0x70
[    3.797704]  [<ffffffff810b0677>] __blocking_notifier_call_chain+0x47/0x60
[    3.797706]  [<ffffffff810b06a1>] blocking_notifier_call_chain+0x11/0x20
[    3.797712]  [<ffffffff813710f6>] fb_notifier_call_chain+0x16/0x20
[    3.797715]  [<ffffffff81373b6a>] register_framebuffer+0x24a/0x330
[    3.797719]  [<ffffffff8141f117>] drm_fb_helper_initial_config+0x237/0x3d0
[    3.797723]  [<ffffffff814d80b3>] intel_fbdev_initial_config+0x13/0x30
[    3.797725]  [<ffffffff810b1bf5>] async_run_entry_fn+0x35/0xf0
[    3.797730]  [<ffffffff810a9101>] process_one_work+0x151/0x400
[    3.797733]  [<ffffffff810a93f7>] worker_thread+0x47/0x480
[    3.797735]  [<ffffffff810a93b0>] ? process_one_work+0x400/0x400
[    3.797738]  [<ffffffff810a93b0>] ? process_one_work+0x400/0x400
[    3.797742]  [<ffffffff810a6519>] ? call_usermodehelper_exec_async+0x129/0x140
[    3.797745]  [<ffffffff810aeb17>] kthread+0xc7/0xe0
[    3.797748]  [<ffffffff810aea50>] ? __kthread_parkme+0x70/0x70
[    3.797750]  [<ffffffff810a63f0>] ? proc_cap_handler+0x180/0x180
[    3.797756]  [<ffffffff8199e592>] ret_from_fork+0x22/0x30
[    3.797758] ---[ end trace bf889451a79aaa0e ]---
[    3.919105] Console: switching to colour frame buffer device 170x48
[    4.177775] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device