Oh, and call traces for comparison (I'm attaching first traces after boot, there are always multiple ones in the log, the latter differing slightly, like having a call to i9xx_crtc_disable):

4.3.0-040300-generic #201511020949
 Call Trace:
  [<ffffffff813a4c94>] dump_stack+0x44/0x60
  [<ffffffff81078052>] warn_slowpath_common+0x82/0xc0
  [<ffffffff8107814a>] warn_slowpath_null+0x1a/0x20
  [<ffffffffc004d2fe>] drm_atomic_check_only+0x46e/0x540 [drm]
  [<ffffffffc004d4bd>] ? drm_atomic_set_fb_for_plane+0x2d/0x90 [drm]
  [<ffffffffc004d3e7>] drm_atomic_commit+0x17/0x60 [drm]
  [<ffffffffc0193355>] intel_get_load_detect_pipe+0x3d5/0x530 [i915]
  [<ffffffffc01c96fd>] intel_tv_detect+0x13d/0x5f0 [i915]
  [<ffffffffc0047d5f>] ? drm_get_edid+0x2f/0x3d0 [drm]
  [<ffffffffc00cfc35>] drm_helper_probe_single_connector_modes_merge_bits+0x235/0x4d0 [drm_kms_helper]
  [<ffffffffc00cfee3>] drm_helper_probe_single_connector_modes+0x13/0x20 [drm_kms_helper]
  [<ffffffffc00db704>] drm_fb_helper_initial_config+0x74/0x3e0 [drm_kms_helper]
  [<ffffffffc01a2deb>] intel_fbdev_initial_config+0x1b/0x20 [i915]
  [<ffffffff81098928>] async_run_entry_fn+0x48/0x150
  [<ffffffff8108ff1a>] process_one_work+0x1aa/0x440
  [<ffffffff810901fb>] worker_thread+0x4b/0x4c0
  [<ffffffff817aedac>] ? __schedule+0x36c/0x980
  [<ffffffff810901b0>] ? process_one_work+0x440/0x440
  [<ffffffff810901b0>] ? process_one_work+0x440/0x440
  [<ffffffff810960f9>] kthread+0xc9/0xe0
  [<ffffffff81096030>] ? kthread_create_on_node+0x180/0x180
  [<ffffffff817b33cf>] ret_from_fork+0x3f/0x70
  [<ffffffff81096030>] ? kthread_create_on_node+0x180/0x180
 ---[ end trace cb8c0d778aaecb5a ]---


4.4.1-040401-generic #201601311534:
 Call Trace:
  [<ffffffff813c8e14>] dump_stack+0x44/0x60
  [<ffffffff8107dba2>] warn_slowpath_common+0x82/0xc0
  [<ffffffff8107dc3c>] warn_slowpath_fmt+0x5c/0x80
  [<ffffffff810bfa25>] ? finish_wait+0x55/0x70
  [<ffffffffc002d2a5>] drm_wait_one_vblank+0x1b5/0x1c0 [drm]
  [<ffffffff810bfec0>] ? wake_atomic_t_function+0x60/0x60
  [<ffffffffc01d66a9>] intel_get_load_detect_pipe+0x529/0x530 [i915]
  [<ffffffffc020fbfd>] intel_tv_detect+0x13d/0x5f0 [i915]
  [<ffffffffc004103e>] ? drm_get_edid+0x3e/0x3f0 [drm]
  [<ffffffff817fcdd6>] ? schedule_hrtimeout_range_clock.part.23+0xa6/0x150
  [<ffffffffc0100da5>] drm_helper_probe_single_connector_modes_merge_bits+0x235/0x4d0 [drm_kms_helper]
  [<ffffffffc0101053>] drm_helper_probe_single_connector_modes+0x13/0x20 [drm_kms_helper]
  [<ffffffffc010d05e>] drm_fb_helper_initial_config+0xae/0x420 [drm_kms_helper]
  [<ffffffffc01e681b>] intel_fbdev_initial_config+0x1b/0x20 [i915]
  [<ffffffff8109f628>] async_run_entry_fn+0x48/0x150
  [<ffffffff8109688a>] process_one_work+0x1aa/0x440
  [<ffffffff81096b6b>] worker_thread+0x4b/0x4c0
  [<ffffffff81096b20>] ? process_one_work+0x440/0x440
  [<ffffffff8109cce8>] kthread+0xd8/0xf0
  [<ffffffff8109cc10>] ? kthread_create_on_node+0x1a0/0x1a0
  [<ffffffff817fdf4f>] ret_from_fork+0x3f/0x70
  [<ffffffff8109cc10>] ? kthread_create_on_node+0x1a0/0x1a0
 ---[ end trace fd397c034408c00f ]---


4.8.0-22-generic #24-Ubuntu
 Call Trace:
  [<ffffffffa222f5d2>] dump_stack+0x63/0x81
  [<ffffffffa1e82e5b>] __warn+0xcb/0xf0
  [<ffffffffa1e82edf>] warn_slowpath_fmt+0x5f/0x80
  [<ffffffffa1ec6ef5>] ? finish_wait+0x55/0x70
  [<ffffffffc0289c06>] drm_wait_one_vblank+0x1b6/0x1c0 [drm]
  [<ffffffffa1ec73a0>] ? wake_atomic_t_function+0x60/0x60
  [<ffffffffc04a95a2>] intel_get_load_detect_pipe+0x662/0x680 [i915]
  [<ffffffffc04e591f>] intel_tv_detect+0x13f/0x5d0 [i915]
  [<ffffffffc034b03b>] drm_helper_probe_single_connector_modes+0x27b/0x520 [drm_kms_helper]
  [<ffffffffc0359bbe>] drm_fb_helper_initial_config+0xae/0x430 [drm_kms_helper]
  [<ffffffffc04bed08>] intel_fbdev_initial_config+0x18/0x30 [i915]
  [<ffffffffa1ea6627>] async_run_entry_fn+0x37/0x150
  [<ffffffffa1e9d61c>] process_one_work+0x1fc/0x4b0
  [<ffffffffa1e9d91b>] worker_thread+0x4b/0x500
  [<ffffffffa1e9d8d0>] ? process_one_work+0x4b0/0x4b0
  [<ffffffffa1e9d8d0>] ? process_one_work+0x4b0/0x4b0
  [<ffffffffa1ea3c18>] kthread+0xd8/0xf0
  [<ffffffffa269f29f>] ret_from_fork+0x1f/0x40
  [<ffffffffa1ea3b40>] ? kthread_create_on_node+0x1e0/0x1e0
 ---[ end trace 4d6ade8c54672b71 ]---