Since ugrade to 4.3.3 on a HP dv6000 I get the following warning.
It wasn't here in 4.2.x kernel series.
Other than this warning, everything seems to works fine after that.

pci 0000:00:1e.0: enabling device (0004 -> 0007)
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6 at drivers/gpu/drm/drm_atomic.c:491 drm_atomic_check_only+0x42f/0x5a0()
Modules linked in:
CPU: 1 PID: 6 Comm: kworker/u4:0 Not tainted 4.3.3 #1
Hardware name: Hewlett-Packard HP Pavilion dv6000 (GH906EA#ABF)  /30BB, BIOS F.2E      03/22/2010
Workqueue: events_unbound async_run_entry_fn
 00000000 00000000 f6483b90 c126173c 00000000 f6483bc0 c103ec3d c1822a38
 00000001 00000006 c1884cd6 000001eb c1343c2f c1343c2f f65ab000 f5d8f898
 f5d8f890 f6483bd0 c103eced 00000009 00000000 f6483c1c c1343c2f 00000558
Call Trace:
 [<c126173c>] dump_stack+0x48/0x6c
 [<c103ec3d>] warn_slowpath_common+0x7d/0xb0
 [<c1343c2f>] ? drm_atomic_check_only+0x42f/0x5a0
 [<c1343c2f>] ? drm_atomic_check_only+0x42f/0x5a0
 [<c103eced>] warn_slowpath_null+0x1d/0x20
 [<c1343c2f>] drm_atomic_check_only+0x42f/0x5a0
 [<c1343033>] ? drm_atomic_set_crtc_for_plane+0x73/0x100
 [<c1343db1>] drm_atomic_commit+0x11/0x50
 [<c13a61f1>] intel_get_load_detect_pipe+0x3a1/0x5d0
 [<c13db246>] intel_tv_detect+0xe6/0x5e0
 [<c133e1a0>] ? drm_get_edid+0x20/0x3e0
 [<c16e9f01>] ? hrtimer_nanosleep_restart+0x11/0x70
 [<c131c1b3>] drm_helper_probe_single_connector_modes_merge_bits+0x2a3/0x450
 [<c106134c>] ? update_curr+0x9c/0xe0
 [<c131c372>] drm_helper_probe_single_connector_modes+0x12/0x20
 [<c1325799>] drm_fb_helper_probe_connector_modes.isra.7+0x39/0x60
 [<c132667b>] drm_fb_helper_initial_config+0x3b/0x360
 [<c105963d>] ? finish_task_switch+0x5d/0x140
 [<c13b62b4>] intel_fbdev_initial_config+0x14/0x20
 [<c1057b31>] async_run_entry_fn+0x31/0xd0
 [<c16e7977>] ? __schedule+0x1e7/0x7c0
 [<c105100e>] process_one_work+0xee/0x2b0
 [<c10512bd>] worker_thread+0xed/0x410
 [<c10511d0>] ? process_one_work+0x2b0/0x2b0
 [<c1055b66>] kthread+0x96/0xb0
 [<c16eab41>] ret_from_kernel_thread+0x21/0x30
 [<c1055ad0>] ? kthread_create_on_node+0x100/0x100
---[ end trace ab46bc531787df58 ]---
fbcon: inteldrmfb (fb0) is primary device
ata6: port disabled--ignoring