Bug 94822 - System hangs when some video output is disabled/enabled on Skylake platform in double/triple display configuration
Summary: System hangs when some video output is disabled/enabled on Skylake platform i...
Status: CLOSED FIXED
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-04-04 16:32 UTC by Edgar Cherkasov
Modified: 2016-09-19 15:22 UTC (History)
2 users (show)

See Also:
i915 platform: SKL
i915 features: display/watermark

Attachments
Dmesg log, xrandr and intel_reg_dump output (283.35 KB, application/x-bzip)
2016-04-04 16:32 UTC, Edgar Cherkasov 		no flags Details
FB Connector Patch #1 (2.17 KB, patch)
2016-05-04 20:52 UTC, Jim Bride 		no flags Details | Splinter Review
FB Connector Patch #2 (1.95 KB, patch)
2016-05-04 20:53 UTC, Jim Bride 		no flags Details | Splinter Review
kms test results (8.68 KB, text/x-log)
2016-05-05 12:41 UTC, Edgar Cherkasov 		no flags Details
test script (193 bytes, application/x-shellscript)
2016-05-05 12:41 UTC, Edgar Cherkasov 		no flags Details
errors on display before system hangs (164 bytes, text/x-log)
2016-05-05 12:42 UTC, Edgar Cherkasov 		no flags Details
SKL-Y_4.6-rc6-447f243_kern.log (163.00 KB, text/plain)
2016-05-09 13:22 UTC, cprigent 		no flags Details
View All

Description Edgar Cherkasov 2016-04-04 16:32:08 UTC 
Created attachment 122705 [details]
Dmesg log, xrandr and intel_reg_dump output

==Reproduce steps==
-------------------------------

How to reproduce:
1. Connect at least two displays to Intel Skylake platform;
2. Boot some decent Linux on it;
3. If system successfully boots up, try to manually disable/enable some video output, e.g. via xrandr:
    xrandr --output eDP1 --off
    xrandr --outout eDP1 --auto
Please note that several attempts may be required.
4. If it does not hang, try to enable/disable different video outputs:
    xrandr --output HDMI1 --off
    xrandr --output HDMI1 --auto
    or
    xrandr --output DP1 --off
    xrandr --output DP1 --auto
5. After these actions, our system hangs in 100% cases.

==Bug detailed description==
-----------------------------------------

We have some Skylake platform(a prototype board from some vendor) with three video outputs:
- 2xDDIx4(DVI/HDMI/DP);
- 1xLVDS(PTN3460 is used to convert eDPx2 to LVDS).

The problem is that Linux(latest Yocto and Ubuntu) sometimes hangs during boot. When we tried to investigate this issue we had discovered that the problem is related to video subsystem and:
- it can be reproduced only when two or three displays are connected to the board;
- is can be reproduced manually(several dozen attempts may be required) by switching on/off some video output via xrandr;
- it's more likely that the system will hang during turning on/off the eDP channel than DDI;
- the system locks up completely so it is not possible to debug the issue further;
- the system hangs when the connected display is physically turned on/off (and not at the moment when xrandr is issued in console);
- when system does not hang, the following calltrace can be observed in dmesg after issuing xrandr command:

[  456.516554] WARNING: CPU: 2 PID: 695 at
/home/kernel/COD/linux/drivers/gpu/drm/i915/intel_pm.c:3633 
skl_update_other_pipe_wm+0x16c/0x180 [i915]
[  456.516559] WARN_ON(!wm_changed)
[  456.516564] Modules linked in:
[  456.516569]  bnep nls_iso8859_1 snd_soc_skl intel_rapl 
snd_soc_skl_ipc x86_pkg_temp_thermal intel_powerclamp snd_soc_sst_ipc 
coretemp snd_soc_sst_dsp snd_hda_codec_hdmi kvm_intel snd_hda_ext_core 
snd_hda_codec_realtek snd_soc_sst_match kvm snd_hda_codec_generic 
snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine joydev input_leds 
dw_dmac_core irqbypass snd_hda_intel snd_hda_codec snd_hda_core 
crct10dif_pclmul snd_hwdep snd_pcm 8250_dw i2c_designware_platform 
i2c_designware_core snd_seq_midi hci_uart crc32_pclmul 
ghash_clmulni_intel aesni_intel btbcm aes_x86_64 snd_seq_midi_event 
btqca btintel lrw snd_rawmidi gf128mul bluetooth glue_helper snd_seq 
snd_seq_device ablk_helper snd_timer cryptd idma64 virt_dma snd 
intel_lpss_pci intel_lpss_acpi intel_lpss mei_me soundcore mei acpi_pad 
mac_hid intel_pch_thermal
[  456.516675]  acpi_als kfifo_buf industrialio parport_pc ppdev lp 
parport autofs4 hid_generic usbhid i915 e1000e i2c_algo_bit ptp 
drm_kms_helper pps_core syscopyarea sysfillrect sysimgblt fb_sys_fops 
sdhci_pci ahci sdhci drm libahci wmi i2c_hid hid video 
pinctrl_sunrisepoint pinctrl_intel fjes
[  456.516734] CPU: 2 PID: 695 Comm: Xorg Tainted: G W  4.6.0-994-generic #201603312200
[  456.516745] Hardware name: Default string Default string/SKYBAY, BIOS 
5.11 12/07/2015
[  456.516751]  0000000000000286 0000000002f3854e ffff88026166f988 ffffffff813ee8c3
[  456.516762]  ffff88026166f9d8 0000000000000000 ffff88026166f9c8 ffffffff8108275b
[  456.516771]  00000e3101b60400 ffff880263aff000 ffff88025dc49fa8 ffff88025ead7000
[  456.516780] Call Trace:
[  456.516799]  [<ffffffff813ee8c3>] dump_stack+0x63/0x90
[  456.516811]  [<ffffffff8108275b>] __warn+0xcb/0xf0
[  456.516821]  [<ffffffff810827df>] warn_slowpath_fmt+0x5f/0x80
[  456.516891]  [<ffffffffc01e17fc>] skl_update_other_pipe_wm+0x16c/0x180 [i915]
[  456.516956]  [<ffffffffc01e1995>] skl_update_wm+0x185/0x670 [i915]
[  456.517019]  [<ffffffffc01e578e>] intel_update_watermarks+0x1e/0x30 [i915]
[  456.517112]  [<ffffffffc024f8c1>] intel_atomic_commit+0x471/0xdf0 [i915]
[  456.517163]  [<ffffffffc008b2ac>] ? drm_ut_debug_printk+0x6c/0x90 [drm]
[  456.517226]  [<ffffffffc00a2df7>] drm_atomic_commit+0x37/0x60 [drm]
[  456.517256]  [<ffffffffc0157f2a>] drm_atomic_helper_set_config+0x7a/0xb0 [drm_kms_helper]
[  456.517310]  [<ffffffffc0092862>] drm_mode_set_config_internal+0x62/0x100 [drm]
[  456.517363]  [<ffffffffc00967b0>] drm_mode_setcrtc+0x3e0/0x500 [drm]
[  456.517402]  [<ffffffffc0087ab2>] drm_ioctl+0x152/0x540 [drm]
[  456.517448]  [<ffffffffc00963d0>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
[  456.517459]  [<ffffffff81233501>] do_vfs_ioctl+0xa1/0x5b0
[  456.517470]  [<ffffffff8122158e>] ? ____fput+0xe/0x10
[  456.517479]  [<ffffffff810a1258>] ? task_work_run+0x78/0x90
[  456.517486]  [<ffffffff81233a89>] SyS_ioctl+0x79/0x90
[  456.517499]  [<ffffffff81839fb6>] entry_SYSCALL_64_fastpath+0x1e/0xa8

Similar errors/issues can be found on bugzilla, but we are not sure that they are related to our problem:
https://bugs.freedesktop.org/show_bug.cgi?id=94122  (this one can be reproduced on our side too)
https://bugs.freedesktop.org/show_bug.cgi?id=93578
https://bugs.freedesktop.org/show_bug.cgi?id=92181
https://bugs.freedesktop.org/show_bug.cgi?id=89055

We have also tried the latest versions of i915 driver from git - no luck.

Please tell if any additional information/testing are needed. Due to lock-up of the system, we have managed to collect only logs below.

==Environment info==
--------------------

$ uname -m
x86_64

$ uname -r
4.6.0-994-generic

$ lsb_release -a
No LSB modules are available.
Distributor ID:    Ubuntu
Description:    Ubuntu Xenial Xerus (development branch)
Release:    16.04
Codename:    xenial

$ dpkg -s libdrm2 | grep 'Version'
Version: 2.4.67+git1603290630.ea78c1~gd~x

$ dpkg -s libdrm-intel1 | grep 'Version'
Version: 2.4.67+git1603290630.ea78c1~gd~x

Graphics adapter:
00:02.0 VGA compatible controller: Intel Corporation Skylake Integrated Graphics (rev 07) (prog-if 00 [VGA controller])
	DeviceName:  Onboard IGD
	Subsystem: Intel Corporation Skylake Integrated Graphics
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 277
	Region 0: Memory at de000000 (64-bit, non-prefetchable) [size=16M]
	Region 2: Memory at c0000000 (64-bit, prefetchable) [size=256M]
	Region 4: I/O ports at f000 [size=64]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [40] Vendor Specific Information: Len=0c <?>
	Capabilities: [70] Express (v2) Root Complex Integrated Endpoint, MSI 00
		DevCap:	MaxPayload 128 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
			MaxPayload 128 bytes, MaxReadReq 128 bytes
		DevSta:	CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
		DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF Not Supported
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
	Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
		Address: fee00018  Data: 0000
	Capabilities: [d0] Power Management version 2
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [100 v1] #1b
	Capabilities: [200 v1] Address Translation Service (ATS)
		ATSCap:	Invalidate Queue Depth: 00
		ATSCtl:	Enable-, Smallest Translation Unit: 00
	Capabilities: [300 v1] #13
	Kernel driver in use: i915
	Kernel modules: i915
Comment 1 Jim Bride 2016-05-04 20:52:32 UTC 
Created attachment 123470 [details] [review]
FB Connector Patch #1
Comment 2 Jim Bride 2016-05-04 20:53:05 UTC 
Created attachment 123471 [details] [review]
FB Connector Patch #2
Comment 3 Jim Bride 2016-05-04 20:58:13 UTC 
There are a couple of odd things that I’ve seen while looking over the first dmesg log.  The first is that the sink devices advertise that they only support up to 2.7Gbps transfer rate, which makes me suspect that they are older models. Could you please tell us the make and model numbers of the displays in question?  The second is that there are quite a number of watermark WARNs.  The kernel log lists the version as 4.6.999, so I really don’t have a clue specifically how recent this is, and I have to assume that it’s based on the kernel.org kernel.  There have been some fixes in the watermarking area recently, so it would be helpful to try and reproduce this issue using the same hardware and drm-intel-nightly (assuming this is not drm-intel with the version info changed.) Finally, although the stated reason for the patches referenced in the thread is DP MST, it might be worth trying the two attached patches on top of drm-intel-nightly, assuming the problem reproduces against that kernel.  The issue being fixed is exacerbated by MST, but it is a general racy problem with the frame buffer connector counting if I’m interpreting the information correctly.
Comment 4 Edgar Cherkasov 2016-05-05 12:39:46 UTC 
(In reply to Jim Bride from comment #3)

Hi Jim,

thanks a lot for your feedback!

First of all let me inform your regarding the state of the main
problem(Linux hangs when video output is disabled/enabled during boot) -
it can't be reproduced with vanilla 4.6.rc5 kernel.

And please find answers to your questions below:

> There are a couple of odd things that I’ve seen while looking over the first
> dmesg log.  The first is that the sink devices advertise that they only
> support up to 2.7Gbps transfer rate, which makes me suspect that they are
> older models. Could you please tell us the make and model numbers of the
> displays in question?

This can be caused by our DP to VGA and DP to DVI converters. If needed
I can repeat the test using a "pure" DP display without any converters.
Description of our current h/w configuration:

1) First DDI output -> DP to DVI-I converter(Chrontel CH7318C) -> DVI
display(Acer V223W);

2) Second DDI output -> DP to VGA converter(noname) -> VGA
display(RoverScan JM678);

3) eDP output -> on-board eDP to LVDS converter(PTN3460) -> LVDS
display(LG LB121S03).

> The second is that there are quite a number of
> watermark WARNs.  The kernel log lists the version as 4.6.999, so I really
> don’t have a clue specifically how recent this is, and I have to assume that
> it’s based on the kernel.org kernel. 

These tests were performed with the latest at that time(first days of
April) version of drm-intel-nightly from prebuilt Ubuntu repository:
http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/
If needed, I can try to find the exact version.

> There have been some fixes in the
> watermarking area recently, so it would be helpful to try and reproduce this
> issue using the same hardware and drm-intel-nightly (assuming this is not
> drm-intel with the version info changed.)

I've tried the latest drm-intel-nightly from the same Ubuntu repository:
cod/tip/drm-intel-nightly/2016-05-05
bbb6a0d936b5648b31f173d47f93f389a6c6b653
and, unfortunately, all the same - system hangs during the execution of
kms_plane test from intel-gpu-tools. The only difference is broken
S3(but it does not relate to Intel drm). Please find logs in the
attachment.

> Finally, although the stated
> reason for the patches referenced in the thread is DP MST, it might be worth
> trying the two attached patches on top of drm-intel-nightly, assuming the
> problem reproduces against that kernel.  The issue being fixed is
> exacerbated by MST, but it is a general racy problem with the frame buffer
> connector counting if I’m interpreting the information correctly.

Thanks! I will give it a try and provide a feedback in 1-2 days.

Summary:
As the problem can't be reproduced on vanilla 4.6.rc5 kernel, the bug
can be closed, but:
 - I still want to test the attached patches and provide feedback;
 - please tell if additional experiments/information are needed(testing
on pure DP display, testing different kernels, different versions of
drm-intel-nightly, ...).

Best regards,
Edgar Cherkasov.
Comment 5 Edgar Cherkasov 2016-05-05 12:41:26 UTC 
Created attachment 123494 [details]
kms test results

On "Testing connector eDP-1 using pipe C plane 1" system hangs
Comment 6 Edgar Cherkasov 2016-05-05 12:41:58 UTC 
Created attachment 123495 [details]
test script
Comment 7 Edgar Cherkasov 2016-05-05 12:42:58 UTC 
Created attachment 123496 [details]
errors on display before system hangs
Comment 8 dog 2016-05-05 14:14:35 UTC 
Intel OTC graphics driver QA performed tests using eDP+HDMI on 3 different SKL platforms… (a production one, SKL-y and SKL-H)

In all three configurations, the bug was not reproducible using latest kernel and graphics stack (The platform never hung)

Next QA test is to connect two displays on the platform (+eDP that makes 3 pipes), unfortunately the platforms QA has available have only 2 pipes available , eDP+HDMI. Testing will be done later ths week on a non-production platform with 3 pipes in order to test this as described in the bug.

Note that the bug report is focused on Fedora 22, a distro that is a year old.
Comment 9 Edgar Cherkasov 2016-05-05 15:08:49 UTC 
(In reply to dog from comment #8)
> Intel OTC graphics driver QA performed tests using eDP+HDMI on 3 different
> SKL platforms… (a production one, SKL-y and SKL-H)
> 
> In all three configurations, the bug was not reproducible using latest
> kernel and graphics stack (The platform never hung)
> 
> Next QA test is to connect two displays on the platform (+eDP that makes 3
> pipes), unfortunately the platforms QA has available have only 2 pipes
> available , eDP+HDMI. Testing will be done later ths week on a
> non-production platform with 3 pipes in order to test this as described in
> the bug.
> 
> Note that the bug report is focused on Fedora 22, a distro that is a year
> old.

Thank you for the information !

I tried to boot Fedora 22 with 4.0.4-301.fc22 kernel with enabled preliminary hw support, as result system hangs then booting. Second I boot system without preliminary hw support and run i915 manually. As result - system hangs then i915 loads.

Best regards,
Edgar Cherkasov.
Comment 10 Edgar Cherkasov 2016-05-06 12:00:57 UTC 
Hi Jim,

I have tried latest drm-intel-nightly(from Ubuntu repository) with
patches from the attachments:
 - system still hangs during kms_plane test(in the same place with the
same error as without these patches. Refer to log here:
https://bugs.freedesktop.org/show_bug.cgi?id=94822#c5 )
 - but I haven't tried yes to reproduce the "main" problem with these
patches(kernel hangs during boot when several displays are connected).
I'm going to provide the results of this test on Tuesday.

It seems that there is some mess in the discussion. Let me put it in
order:
 - "main problem"(kernel freezes during boot) can't be reproduced with
vanilla 4.6.rc5 kernel;
 - but kms_plane test still hangs on all available
kernels/drm-intel-nighty with and without patches from
https://bugs.freedesktop.org/show_bug.cgi?id=94822#c1 and
https://bugs.freedesktop.org/show_bug.cgi?id=94822#c2

The second problem is not important for me, but I can conduct more tests
or collect more detailed debug output if needed.

Please also note that  I'm using SKL-U SoC system, not Y or H variant.
 
Best regards,
Edgar Cherkasov.
Comment 11 cprigent 2016-05-09 13:22:50 UTC 
Created attachment 123571 [details]
SKL-Y_4.6-rc6-447f243_kern.log

I reproduced a similar problem on SKL-Y with fresh kernel.

Steps:
-------
1. Connect HDMI and DP screens
2. Boot
3. xrandr --output eDP1 --off
4. xrandr --outout eDP1 --auto

Actual result:
----------------
4. eDP stays black. Command does not respond

Info
-----
Could be the same as bug 89055

Not reproduced with 4.6 rc6 from https://cgit.freedesktop.org/drm-intel/
commit 871c895c2d3192a93a701b31d2576184ab070c66
Author: Rodrigo Vivi <rodrigo.vivi@intel.com>
Date:   Thu May 5 16:49:48 2016 -0700
drm-intel-nightly: 2016y-05m-05d-23h-49m-21s UTC integration manifest

Setup
------
Hardware
Platform: 
CPU : Intel(R) Core(TM) m5-6Y57 CPU @ 1.10GHz (family: 6, model: 78  stepping: 3)
MCP : SKL-Y  D1 2+2
QDF : QJK9 
CPU : SKL D0
Chipset PCH: Sunrise Point LP C0       
CRB : SKY LAKE Y LPDDR3 RVP3 CRB FAB2
Software 
Linux OS : Ubuntu 16.10 64 bits
BIOS : SKLSE2R1.R00.B104.B01.1511110114
ME FW : 11.0.0.1191
Ksc (EC FW): 1.20
Kernel: drm-intel-nightly 4.6.0-rc6 447f243 from http://cgit.freedesktop.org/drm-intel
   commit 447f2438e5ee3e9bb7d5cbe88fc44cdff74cc165
   Author: Daniel Vetter <daniel.vetter@ffwll.ch>
   Date:   Sun May 8 18:21:27 2016 +0200
   drm-intel-nightly: 2016y-05m-08d-16h-21m-00s UTC integration manifest
drm: libdrm-2.4.67-11 ea78c17 from http://cgit.freedesktop.org/mesa/drm/
xorg-server-1.18.0-254 44e1c97 from git://git.freedesktop.org/git/xorg/xserver
mesa: mesa-11.1.2 7bcd827 from http://cgit.freedesktop.org/mesa/mesa/
cairo: tag 1.15.2 db8a7f1 from http://cgit.freedesktop.org/cairo
libva: libva-1.7.0-1 2339d10 from http://cgit.freedesktop.org/libva/
vaapi-intel-driver: 1.7.0.pre1 ab8e4e3 from http://cgit.freedesktop.org/vaapi/intel-driver
Comment 12 Edgar Cherkasov 2016-05-10 08:02:30 UTC 
(In reply to cprigent from comment #11)
> Created attachment 123571 [details]
> SKL-Y_4.6-rc6-447f243_kern.log
> 
> I reproduced a similar problem on SKL-Y with fresh kernel.
> 
> Steps:
> -------
> 1. Connect HDMI and DP screens
> 2. Boot
> 3. xrandr --output eDP1 --off
> 4. xrandr --outout eDP1 --auto
> 
> Actual result:
> ----------------
> 4. eDP stays black. Command does not respond
> 
> Info
> -----
> Could be the same as bug 89055
> 
> Not reproduced with 4.6 rc6 from https://cgit.freedesktop.org/drm-intel/
> commit 871c895c2d3192a93a701b31d2576184ab070c66
> Author: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Date:   Thu May 5 16:49:48 2016 -0700
> drm-intel-nightly: 2016y-05m-05d-23h-49m-21s UTC integration manifest
> 
> Setup
> ------
> Hardware
> Platform: 
> CPU : Intel(R) Core(TM) m5-6Y57 CPU @ 1.10GHz (family: 6, model: 78 
> stepping: 3)
> MCP : SKL-Y  D1 2+2
> QDF : QJK9 
> CPU : SKL D0
> Chipset PCH: Sunrise Point LP C0       
> CRB : SKY LAKE Y LPDDR3 RVP3 CRB FAB2
> Software 
> Linux OS : Ubuntu 16.10 64 bits
> BIOS : SKLSE2R1.R00.B104.B01.1511110114
> ME FW : 11.0.0.1191
> Ksc (EC FW): 1.20
> Kernel: drm-intel-nightly 4.6.0-rc6 447f243 from
> http://cgit.freedesktop.org/drm-intel
>    commit 447f2438e5ee3e9bb7d5cbe88fc44cdff74cc165
>    Author: Daniel Vetter <daniel.vetter@ffwll.ch>
>    Date:   Sun May 8 18:21:27 2016 +0200
>    drm-intel-nightly: 2016y-05m-08d-16h-21m-00s UTC integration manifest
> drm: libdrm-2.4.67-11 ea78c17 from http://cgit.freedesktop.org/mesa/drm/
> xorg-server-1.18.0-254 44e1c97 from
> git://git.freedesktop.org/git/xorg/xserver
> mesa: mesa-11.1.2 7bcd827 from http://cgit.freedesktop.org/mesa/mesa/
> cairo: tag 1.15.2 db8a7f1 from http://cgit.freedesktop.org/cairo
> libva: libva-1.7.0-1 2339d10 from http://cgit.freedesktop.org/libva/
> vaapi-intel-driver: 1.7.0.pre1 ab8e4e3 from
> http://cgit.freedesktop.org/vaapi/intel-driver

I reproduced this on my machine with same results and errors.

Best regards,
Edgar Cherkasov
Comment 13 Jani Nikula 2016-06-16 07:34:56 UTC 
Please try current drm-intel-nightly. At least the 

[  456.516554] WARNING: CPU: 2 PID: 695 at
/home/kernel/COD/linux/drivers/gpu/drm/i915/intel_pm.c:3633 
skl_update_other_pipe_wm+0x16c/0x180 [i915]
[  456.516559] WARN_ON(!wm_changed)


part is fixed now (bug 89055).
Comment 14 Rami 2016-09-19 15:10:36 UTC 
This bug in not reproduced with last nightly kernel 4.8.0-rc7  from https://cgit.freedesktop.org/drm-intel/:
Setup:
======
Hardware
Platform: 
CPU :  Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (family: 6, model: 94  stepping: 3)
Software 
Linux OS : Ubuntu 16.10 64 bits
Kernel:drm-intel-nightly: 2016y-09m-19d-13h-29m-20s UTC integration manifest'
       author: Daniel Vetter <daniel.vetter@ffwll.ch>
       authored_date: Mon Sep 19 13:29:41 2016 +0000
       commit: 24e02e82fe9870ae4951d6e5bb8886097f0aa70b
drm: libdrm-2.4.70-14-g0659558 from http://cgit.freedesktop.org/mesa/drm/
xorg-server-1.18.99.2 from git://git.freedesktop.org/git/xorg/xserver
mesa:  mesa-12.0.0  78b061 from http://cgit.freedesktop.org/mesa/mesa/
cairo: tag 1.15.2 db8a7f1 from http://cgit.freedesktop.org/cairo
libva: libva-1.7.0-50-g7aa2dd9 from http://cgit.freedesktop.org/libva/
vaapi-intel-driver: 1.7.0-136-g36fbd81 from http://cgit.freedesktop.org/vaapi/intel-driver

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.