Comment 21 for bug 1432405

still present in:
-> 3.19.5 and
-> 4.0.0

<snips>
BOOT_IMAGE=/vmlinuz-3.19.5.6 root=UUID=6c3bcf92-5a26-4dde-95e3-78ceb9aaa35b ro i
915.modeset=1 rhgb quiet LANG=de_DE.UTF-8 i915.force_backlight_pmic=0

...
[ 1.213951] [drm] Initialized drm 1.1.0 20060810
[ 1.215856] [drm] Memory usable by graphics device = 2048M
[ 1.215866] checking generic (80000000 8ca000) vs hw (80000000 10000000)
[ 1.215871] fb: switching to inteldrmfb from simple
[ 1.215920] Console: switching to colour dummy device 80x25
[ 1.216086] [drm] Replacing VGA console driver
[ 1.217799] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 1.217804] [drm] Driver supports precise vblank timestamp query.
[ 1.217840] [drm:intel_parse_bios] *ERROR* Unknown element
[ 1.217852] [drm:intel_parse_bios] *ERROR* Sequence elements going beyond block itself. Sequence block parsing failed
[ 1.259808] vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem
[ 1.281232] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)
[ 1.282662] acpi device:21: registered as cooling_device4
[ 1.282866] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input1
[ 1.282938] [drm] Initialized i915 1.6.0 20141121 for 0000:00:02.0 on minor 0
...
...
[ 1.289898] i8042: PNP: No PS/2 controller found. Probing ports directly.
[ 1.336417] [drm] GMBUS [i915 gmbus dpb] timed out, falling back to bit banging on pin 5
[ 1.350512] fbcon: inteldrmfb (fb0) is primary device
[ 2.333926] i8042: No controller found
...
[ 2.536902] Console: switching to colour frame buffer device 150x120
[ 2.573929] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
[ 2.573932] i915 0000:00:02.0: registered panic notifier
...
[ 3.833614] EXT4-fs (mmcblk0p4): mounted filesystem with ordered data mode. Opts: (null)
[ 3.935493] ------------[ cut here ]------------
[ 3.935536] WARNING: CPU: 3 PID: 262 at drivers/gpu/drm/drm_irq.c:1130 drm_wait_one_vblank+0x177/0x180()
[ 3.935546] vblank wait timed out on crtc 0
[ 3.935553] Modules linked in: ax88179_178a usbnet mii
[ 3.935588] CPU: 3 PID: 262 Comm: plymouthd Not tainted 3.19.5.6 #83

If you need more debugs, I have plenty of them...