Hi,
sorry for the delay, this is a friend's laptop. The failure to suspend was there in 4.5.0-040500-generic package, but it is fixed in 4.6.0-040600rc1-generic.

however, a kernel bug with a similar trace as the bug in kernel package 4.4.0-16-generic (see below). All tested versions suffer from flickering in the screen that appears at random intervals. The flickering disappears for a while in version 4.6.0 after a suspend/resume cycle.



[ 66.775902] ------------[ cut here ]------------
[ 66.775928] WARNING: CPU: 1 PID: 166 at
/home/kernel/COD/linux/drivers/gpu/drm/i915/intel_uncore.c:649 __unclaimed_reg_debug+0x80/0x90
[i915]
[ 66.775930] Unclaimed register detected before reading register 0x205c
[ 66.775930] Modules linked in: thinkpad_acpi nvram msr pci_stub vboxpci(OE) vboxnetadp(OE)
vboxnetflt(OE) vboxdrv(OE) drbg ansi_cprng ctr ccm bnep uvcvideo dm_crypt videobuf2_vmalloc
videobuf2_memops videobuf2_v4l2 videobuf2_core videodev media btusb btrtl btbcm btintel bluetooth
arc4 iwlmvm mac80211 snd_soc_skl intel_rapl snd_soc_skl_ipc x86_pkg_temp_thermal snd_soc_sst_ipc
intel_powerclamp snd_soc_sst_dsp coretemp snd_hda_ext_core kvm_intel kvm irqbypass
snd_soc_sst_match snd_hda_codec_hdmi iwlwifi snd_soc_core snd_hda_codec_generic crct10dif_pclmul
snd_compress ac97_bus snd_pcm_dmaengine crc32_pclmul dw_dmac_core ghash_clmulni_intel rtsx_pci_ms
snd_hda_intel snd_hda_codec snd_hda_core memstick snd_hwdep aesni_intel snd_pcm snd_seq_midi
aes_x86_64 snd_seq_midi_event lrw cfg80211 snd_rawmidi gf128mul
[ 66.775956] glue_helper snd_seq snd_seq_device ablk_helper snd_timer cryptd mei_me mei snd
ideapad_laptop sparse_keymap shpchp input_leds joydev soundcore intel_pch_thermal serio_raw tpm_crb
acpi_pad mac_hid parport_pc ppdev lp parport autofs4 amdkfd rtsx_pci_sdmmc amd_iommu_v2 radeon i915
ttm i2c_algo_bit drm_kms_helper syscopyarea psmouse sysfillrect sysimgblt fb_sys_fops rtsx_pci drm
r8169 ahci mii libahci wmi video fjes
[ 66.775975] CPU: 1 PID: 166 Comm: kworker/u16:3 Tainted: G OE 4.6.0-040600rc1-generic
#201603261930
[ 66.775976] Hardware name: LENOVO 80LM/Lenovo B51-80, BIOS D7CN15WW(V1.01) 08/12/2015
[ 66.775986] Workqueue: i915-hangcheck i915_hangcheck_elapsed [i915]
[ 66.775987] 0000000000000086 000000000e719fb3 ffff88006f9dfc18 ffffffff813ee833
[ 66.775989] ffff88006f9dfc68 0000000000000000 ffff88006f9dfc58 ffffffff8108275b
[ 66.775991] 000002896f9dfc60 0000000000000001 0000000000000001 000000000000205c
[ 66.775992] Call Trace:
[ 66.775996] [<ffffffff813ee833>] dump_stack+0x63/0x90
[ 66.775999] [<ffffffff8108275b>] __warn+0xcb/0xf0
[ 66.776000] [<ffffffff810827df>] warn_slowpath_fmt+0x5f/0x80
[ 66.776014] [<ffffffffc01f4dc0>] __unclaimed_reg_debug+0x80/0x90 [i915]
[ 66.776026] [<ffffffffc01fa81b>] gen9_read32+0x30b/0x390 [i915]
[ 66.776038] [<ffffffffc01efc94>] intel_ring_get_active_head+0x84/0xe0 [i915]
[ 66.776047] [<ffffffffc01a74db>] i915_hangcheck_elapsed+0x10b/0x550 [i915]
[ 66.776050] [<ffffffff8102d772>] ? __switch_to+0x2a2/0x550
[ 66.776052] [<ffffffff8109c845>] process_one_work+0x165/0x480
[ 66.776054] [<ffffffff8109cbab>] worker_thread+0x4b/0x500
[ 66.776056] [<ffffffff8109cb60>] ? process_one_work+0x480/0x480
[ 66.776057] [<ffffffff810a2df8>] kthread+0xd8/0xf0
[ 66.776060] [<ffffffff8183a122>] ret_from_fork+0x22/0x40
[ 66.776061] [<ffffffff810a2d20>] ? kthread_create_on_node+0x1a0/0x1a0
[ 66.776062] ---[ end trace ed04d4a8f32f5114 ]---
[ 88.615001] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun