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[Bug 1522922] Re: Screen flickering in Intel i915 driver

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On 2015-07-19T11:17:16+00:00 Furniss-tom wrote:

Created attachment 117243
dmesg

Consistently flickering screen when i915 driver is used with the
N133HSE-EA3 screen of the Lafite 13.3 laptop.  Video here:
https://www.youtube.com/watch?v=0ISthkP7L3o

When i915 driver is disabled (i915.modeset=0), Linux falls back to the
vesa driver and the laptop screen renders correctly.

When an external monitor is connected via HDMI, the i915 driver renders
the external monitor correctly whilst the flickering remains on the
laptop screen.

Earlier versions of this laptop model did not experience this problem,
but the most recent version does (reported by one other user).  I have
no authoritative record of the hardware changes between model versions.

System information:
 - Architecture and kernel: 4.2.0-994-generic #201507142205 SMP Wed Jul 15 02:06:50 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
 - Distribution: Ubuntu 15.04
 - Laptop model: Lafite 13.3 from www.pcspecialist.co.uk
 - Laptop Screen: Chimei N133HSE-EA3
 - Display Conenctor: eDP


$ sudo get-edid | edid-decode
Extracted contents:
header:          00 ff ff ff ff ff ff 00
serial number:   0d ae 61 13 00 00 00 00 07 18
version:         01 04
basic params:    a5 1d 11 78 02
chroma info:     ce 85 a3 57 4e 9d 26 12 50 54
established:     00 00 00
standard:        01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1:    36 36 80 a0 70 38 20 40 2e 1e 24 00 25 a5 10 00 00 18
descriptor 2:    24 24 80 a0 70 38 20 40 2e 1e 24 00 25 a5 10 00 00 18
descriptor 3:    00 00 00 fe 00 43 4d 4e 0a 20 20 20 20 20 20 20 20 20
descriptor 4:    00 00 00 fe 00 4e 31 33 33 48 53 45 2d 45 41 33 0a 20
extensions:      00
checksum:        a1

Manufacturer: CMN Model 1361 Serial Number 0
Made week 7 of 2014
EDID version: 1.4
Digital display
8 bits per primary color channel
DisplayPort interface
Maximum image size: 29 cm x 17 cm
Gamma: 2.20
Supported color formats: RGB 4:4:4
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 138.780 MHz, 293 mm x 165 mm
               1920 1966 1996 2080 hborder 0
               1080 1082 1086 1112 vborder 0
               -hsync -vsync
Detailed mode: Clock 92.520 MHz, 293 mm x 165 mm
               1920 1966 1996 2080 hborder 0
               1080 1082 1086 1112 vborder 0
               -hsync -vsync
ASCII string: CMN
         ASCII string: N133HSE-EA3
 Checksum: 0xa1
EDID block does NOT conform to EDID 1.3!
	Missing name descriptor
	Missing monitor ranges


$ sudo lshw -c video
  *-display
       description: VGA compatible controller
       product: Broadwell-U Integrated Graphics
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:50 memory:b1000000-b1ffffff memory:c0000000-cfffffff ioport:4000(size=64)



$ glxinfo | grep -i vendor
server glx vendor string: SGI
client glx vendor string: Mesa Project and SGI
OpenGL vendor string: Intel Open Source Technology Center


$ glxinfo | grep -i render
direct rendering: Yes
    GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer, 
    GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer, 
OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2) 
    GL_ARB_conditional_render_inverted, GL_ARB_conservative_depth, 
    GL_MESA_texture_signed_rgba, GL_NV_conditional_render, GL_NV_depth_clamp, 
    GL_ARB_conditional_render_inverted, GL_ARB_conservative_depth, 
    GL_NV_conditional_render, GL_NV_depth_clamp, GL_NV_light_max_exponent, 
    GL_OES_element_index_uint, GL_OES_fbo_render_mipmap,

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/0

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On 2015-07-19T11:18:11+00:00 Furniss-tom wrote:

Created attachment 117244
intel-reg-dumper

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/1

------------------------------------------------------------------------
On 2015-07-19T11:18:44+00:00 Furniss-tom wrote:

Created attachment 117245
edid file

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/2

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On 2015-07-19T11:19:26+00:00 Furniss-tom wrote:

Created attachment 117246
xrandr --verbose

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/3

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On 2015-07-19T14:17:03+00:00 Furniss-tom wrote:

Created attachment 117247
xorg log

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/4

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On 2015-08-03T21:25:20+00:00 Jesse Barnes wrote:

Does i915.enable_ips=0 help at all?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/5

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On 2015-08-04T14:27:49+00:00 Furniss-tom wrote:

(In reply to Jesse Barnes from comment #5)
> Does i915.enable_ips=0 help at all?

Same symptoms were observed with i915.enable_ips=0.  Kernel is drm-
intel-nightly 4.2.0-994.201508010158

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/6

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On 2015-08-17T21:26:30+00:00 Rodrigo-vivi wrote:

Hi Tom,
Please let me know the status of few feature while you get this:

sudo cat /sys/kernel/debug/dri/0/i915_edp_psr_status

sudo cat /sys/kernel/debug/dri/0/i915_fbc_status

sudo cat /sys/kernel/debug/dri/0/i915_ips_status

Thanks,
Rodrigo.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/7

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On 2015-08-20T13:52:47+00:00 Furniss-tom wrote:

(In reply to Rodrigo Vivi from comment #7)
> Hi Tom,
> Please let me know the status of few feature while you get this:
> 
> sudo cat /sys/kernel/debug/dri/0/i915_edp_psr_status
> 
> sudo cat /sys/kernel/debug/dri/0/i915_fbc_status
> 
> sudo cat /sys/kernel/debug/dri/0/i915_ips_status
> 
> Thanks,
> Rodrigo.

Hi Rodrigo - those directories (beyond /sys/kernel) don't exist on my
system.  Do I need to enable some kind of additional logging?

Thanks

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/8

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On 2015-09-10T09:40:43+00:00 Oscar Morante wrote:

Hi,
I think I'm running into the same problem on my machine.  But in my case it only happens after the screen goes to sleep (locking in gnome) and sometimes it stays completely black instead of flickering.  You can also see that it renders some garbage from time to time.

https://www.youtube.com/watch?v=YL_9IRsx8Lo

I'm using the kernel packages from Arch Linux's repositories and it only
started happening with version 4.2 (which is on Arch's testing repo
right now).  It works fine with 4.1.6 (in the core repo) except for
occasional 1 frame blackouts.


System information:
 - Architecture and kernel: 4.2.0-3-ARCH #1 SMP PREEMPT Fri Sep 4 20:59:11 UTC 2015 x86_64 GNU/Linux
 - Distribution: Arch Linux
 - Laptop model: Razer Blade 14" (2015)
 - Laptop Screen: (I don't know how to check this :?)
 - Display Conenctor: eDP

I don't see any errors in any of my logs when this happens.  Is there
any debug setting I can use that can help you get more information?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/9

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On 2015-09-10T12:49:45+00:00 Jani-nikula wrote:

I'd like to get an intel_reg dump output ('intel_reg dump' replaces
intel_reg_dumper in recent http://cgit.freedesktop.org/xorg/app/intel-
gpu-tools/) for both before and after loading i915. Alternatively, with
i915.modeset=0 and i915.modeset=1. It should be interesting to see the
difference in register values for both cases.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/10

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On 2015-09-10T14:32:53+00:00 Furniss-tom wrote:

(In reply to Jani Nikula from comment #10)
> I'd like to get an intel_reg dump output ('intel_reg dump' replaces
> intel_reg_dumper in recent
> http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/) for both before and
> after loading i915. Alternatively, with i915.modeset=0 and i915.modeset=1.
> It should be interesting to see the difference in register values for both
> cases.

Hi Jani, I am away from the laptop right now but should be able to
provide the additional information in a few days.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/11

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On 2015-09-11T11:01:42+00:00 Oscar Morante wrote:

Is there any guide I can follow to dump the registers before the module
is loaded?  I did a quick test passing `break=postmount` to the kernel
and chrooting into the rootfs but I couldn't manage to get intel_reg to
work like this.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/12

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On 2015-09-16T14:31:05+00:00 Mm-v wrote:

Same problem here on the Pentium brodwell GT1 model (TopStar U731).

Does it affect any kernel ?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/13

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On 2015-09-21T13:37:23+00:00 Furniss-tom wrote:

(In reply to Jani Nikula from comment #10)
> I'd like to get an intel_reg dump output ('intel_reg dump' replaces
> intel_reg_dumper in recent
> http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/) for both before and
> after loading i915. Alternatively, with i915.modeset=0 and i915.modeset=1.
> It should be interesting to see the difference in register values for both
> cases.

I've uploaded two files:
 - i915.modeset0.txt
 - i915.modeset1.txt

Both contain the output of the command "intel_reg dump", one with
i915.modeset=0, one with i915.modeset=1.

intel-gpu-tools is version 1.11.  Kernel is drm-intel-next,
4.2.0-997-generic #201509120200 SMP Sat Sep 12 02:02:06 UTC 2015 x86_64
x86_64 x86_64 GNU/Linux.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/14

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On 2015-09-21T13:38:29+00:00 Furniss-tom wrote:

Created attachment 118383
intel_reg dump with i915.modeset=0

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/15

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On 2015-09-21T13:40:51+00:00 Furniss-tom wrote:

Created attachment 118384
intel_reg dump with i915.modeset=1

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/16

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On 2015-09-30T13:34:32+00:00 Oscar Morante wrote:

If it helps, this is the output of intel_reg dump before and after it
happens for me.  This is the sequence:

1) Boot into a gnome 3 desktop  (everything works fine)
2) intel_reg dump > intel_reg-dump-ok
3) Lock the screen with gnome (turns off the display)
4) Unlock the screen (here I start getting the flickering)
5) intel_reg dump > intel_reg-dump-flickering

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/17

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On 2015-09-30T13:35:27+00:00 Oscar Morante wrote:

Created attachment 118538
intel_reg dump before the flicker happens

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/18

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On 2015-09-30T13:36:12+00:00 Oscar Morante wrote:

Created attachment 118539
intel_reg dump while the flicker is happening

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/19

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On 2015-10-01T09:14:03+00:00 Jani-nikula wrote:

(In reply to Oscar Morante from comment #17)
> If it helps, this is the output of intel_reg dump before and after it
> happens for me.  This is the sequence:
> 
> 1) Boot into a gnome 3 desktop  (everything works fine)
> 2) intel_reg dump > intel_reg-dump-ok
> 3) Lock the screen with gnome (turns off the display)
> 4) Unlock the screen (here I start getting the flickering)
> 5) intel_reg dump > intel_reg-dump-flickering

Oscar, please add drm.debug=14 module parameter, and attach dmesg all
the way from boot to repeating the above (no need to redo the dumps,
just 1,3,4). Make sure you capture the dmesg for a sequence that
reproduces the issue. Thanks.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/20

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On 2015-10-01T16:48:36+00:00 Oscar Morante wrote:

Created attachment 118563
dmesg with drm.debug=14 (boot -> gnome -> lock -> unlock -> flicker)

There you go.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/21

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On 2015-10-01T16:50:13+00:00 Oscar Morante wrote:

Created attachment 118564
dmesg with drm.debug=14 (boot -> gnome -> lock -> unlock -> flicker)

Oops! I mixed up the files.  This is the good one.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/22

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On 2015-10-08T10:05:14+00:00 Oscar Morante wrote:

I received an update from Arch Linux and now instead of flickering it
stays completely black (but it turns on).

[2015-10-08 08:53] [ALPM] upgraded xf86-video-intel
(1:2.99.917+472+gf0fd4d5-1 -> 1:2.99.917+476+g4e668dd-1)

The Arch package doesn't apply any patches and it get's the source
straight from git, notice the git SHA's between the "+g" and "-1".  I'll
upload more debug logs later.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/23

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On 2015-10-11T08:08:44+00:00 Oscar Morante wrote:

Nevermind, I went to capture the logs and now I get the flicker every
time... I guess it was just coincidence.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/24

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On 2015-10-23T14:32:54+00:00 Oscar Morante wrote:

Reverting these commits "fixes" the problem on my machine :)

  - https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/patch/?id=4e96c97742f4201edf1b0f8e1b1b6b2ac6ff33e7
  - https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/patch/?id=5fa836a9d85975c5f0f1219669523c1f0ac64349

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/25

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On 2015-10-23T14:37:41+00:00 Mm-v wrote:

Great news Oscar Morante !

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/26

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On 2015-10-25T06:51:17+00:00 Oscar Morante wrote:

Yes, I hope it help to find a proper fix :)

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/27

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On 2015-10-26T13:52:30+00:00 Jani-nikula wrote:

(In reply to Oscar Morante from comment #25)
> Reverting these commits "fixes" the problem on my machine :)
> 
>   -
> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/patch/
> ?id=4e96c97742f4201edf1b0f8e1b1b6b2ac6ff33e7
>   -
> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/patch/
> ?id=5fa836a9d85975c5f0f1219669523c1f0ac64349

commit 4e96c97742f4201edf1b0f8e1b1b6b2ac6ff33e7
Author: Mika Kahola <mika.kahola@xxxxxxxxx>
Date:   Wed Apr 29 09:17:39 2015 +0300

    drm/i915: eDP link training optimization

commit 5fa836a9d85975c5f0f1219669523c1f0ac64349
Author: Mika Kahola <mika.kahola@xxxxxxxxx>
Date:   Wed Apr 29 09:17:40 2015 +0300

    drm/i915: DP link training optimization

Cc: Mika.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/28

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On 2015-11-02T08:12:18+00:00 Jani-nikula wrote:

Please try this patch:

http://patchwork.freedesktop.org/patch/msgid/1446223656-27792-1-git-
send-email-ville.syrjala@xxxxxxxxxxxxxxx

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/29

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On 2015-11-02T08:40:21+00:00 Twisted-fall wrote:

I'm having the same problem on 4.2.x and 4.3 and patch suggested by Jani
Nikula doesn't help. Reverting the patches mentioned by Oscar Morante
fixes the problem for both 4.2.x and 4.3

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/30

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On 2015-11-20T13:14:13+00:00 Mika-kahola wrote:

Created attachment 119983
Make DP fast link training option as module parameter

I wasn't able to replicate this issue of flickering screen with the HW
that I had available. However, that doesn't rule out the fact that there
truly is a problem. It seems that there are panels out there that simply
doesn't like to start DP link training with non-zero values.

The patch here makes this fast link training feature as one module
parameter (/sys/module/i915/parameters/enable_dp_flt) so you can enable
or disable the feature depending on panel support. By default this
feature is disabled. The patch applies to drm-intel-nightly.

Please, give this patch a try and report back with dmesg log if the
problem still exists.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/31

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On 2015-11-24T13:45:37+00:00 Lorebett wrote:

I was experiencing the same problem after upgrading to Kubuntu 15.10,
kernel 4.2.0-18-generic (Dell m3800); the flickering happens if I switch
from a lower resolution than the maximal one, 3200x1800, e.g.,
1920x1080).

I tried to apply the latest patch, but it does not apply since I guess
it's too new for the sources of 4.2.0-18-generic.

However, reverting the two commits as mentioned in
https://bugs.freedesktop.org/show_bug.cgi?id=91393#c25 fixes the problem
for me as well!

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/32

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On 2015-11-24T14:22:10+00:00 Furniss-tom wrote:

I applied the patch and it resolved my flickering problem.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/33

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On 2015-11-25T07:39:33+00:00 Kimmo Nikkanen wrote:

Assigning to our QA for verification

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/34

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On 2015-11-25T10:14:09+00:00 Mika-kahola wrote:

(In reply to Tom Furniss from comment #33)
> I applied the patch and it resolved my flickering problem.

Thank you for testing! Unfortunately, it turned out we cannot upstream
that patch as we do not want to add additional module parameters.
Instead, we need to come up with another kind of solution.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/35

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On 2015-11-25T10:23:40+00:00 Mika-kahola wrote:

Created attachment 120109
DP configuration check

This patch adds additional test and disables fast link training feature
if DP link parameters such as link bandwidth, rate selection, lane
count, port clock and bpp. If one of these parameter change the fast
link training is disabled and link is retrained with the link training
parameters starting from zero values. Please, give this patch a go and
report back with dmesg if flickering still exists.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/36

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On 2015-12-01T12:09:31+00:00 Kimmo Nikkanen wrote:

Lowering the priority. 
This is not blocking our work and we haven't been able to reproduce the problem on our side.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/37

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On 2015-12-01T17:32:35+00:00 Lorebett wrote:

(In reply to Mika Kahola from comment #36)
> Created attachment 120109 [details] [review]
> DP configuration check
> 
> This patch adds additional test and disables fast link training feature if
> DP link parameters such as link bandwidth, rate selection, lane count, port
> clock and bpp. If one of these parameter change the fast link training is
> disabled and link is retrained with the link training parameters starting
> from zero values. Please, give this patch a go and report back with dmesg if
> flickering still exists.

To which kernel should this patch be applied?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/38

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On 2015-12-02T06:47:14+00:00 Mika-kahola wrote:

(In reply to Lorenzo Bettini from comment #38)
> (In reply to Mika Kahola from comment #36)
> > Created attachment 120109 [details] [review] [review]
> > DP configuration check
> > 
> > This patch adds additional test and disables fast link training feature if
> > DP link parameters such as link bandwidth, rate selection, lane count, port
> > clock and bpp. If one of these parameter change the fast link training is
> > disabled and link is retrained with the link training parameters starting
> > from zero values. Please, give this patch a go and report back with dmesg if
> > flickering still exists.
> 
> To which kernel should this patch be applied?

This should apply to drm-intel-nightly. I received a feedback concerning
this patch and I updated it. An updated version can be found

https://patchwork.freedesktop.org/patch/66697/

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/39

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On 2015-12-04T04:10:15+00:00 Luke-hutchison wrote:

I see significant flickering for about 2-3 minutes every time I resume
from RAM in Fedora 23 (kernel 4.2.6-300.fc23.x86_64). The problem was
also present in Fedora 22.

- External monitor (Crossover brand), connected via DP
- Intel HD Graphics 4600

Strangely, sometimes opening a terminal window with black background
(even in non-fullscreen mode) stops the flickering, but if I minimize
the window again, the flickering resumes.

I don't see anything strange in the logs.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/40

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On 2015-12-04T07:34:15+00:00 Mika-kahola wrote:

That is a bit strange. Could you provide a dmesg log with the option
drm.debug=0xe?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/41

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On 2015-12-04T16:29:28+00:00 Furniss-tom wrote:

(In reply to Mika Kahola from comment #36)
> Created attachment 120109 [details] [review]
> DP configuration check
> 
> This patch adds additional test and disables fast link training feature if
> DP link parameters such as link bandwidth, rate selection, lane count, port
> clock and bpp. If one of these parameter change the fast link training is
> disabled and link is retrained with the link training parameters starting
> from zero values. Please, give this patch a go and report back with dmesg if
> flickering still exists.

Hi Mika.  Your second patch also fixes the problem for me.  After
removing your first patch and applying the second the flickering issue
did not recur.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/42

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On 2015-12-05T11:00:17+00:00 flux242 wrote:

hi, I'm also experiencing bad flickering of my laptop screen.
I have installed xubuntu 15.10 on Acer C740:

a@chrome:~$ sudo lshw -c video
  *-display               
       description: VGA compatible controller
       product: Broadwell-U Integrated Graphics
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 08
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:43 memory:e0000000-e0ffffff memory:d0000000-dfffffff ioport:1800(size=64)

a@chrome:~$ uname -a
Linux chrome 4.2.0-19-generic #23-Ubuntu SMP Wed Nov 11 11:39:30 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

But today display was blanked after 15 minutes of inactivity and when I woken it up I saw no more flickering and this kernel message:
Dec  5 10:16:48 chrome kernel: [ 3708.390613] [drm:intel_dp_start_link_train [i915]] *ERROR* failed to enable link training

please suggest a way (usingn a kernel parameter) to disable link
training until a bugfix is backported

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/46

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On 2015-12-05T14:19:32+00:00 flux242 wrote:

(In reply to flux242 from comment #43)
> hi, I'm also experiencing bad flickering of my laptop screen.
> I have installed xubuntu 15.10 on Acer C740:
> 
> a@chrome:~$ sudo lshw -c video
>   *-display               
>        description: VGA compatible controller
>        product: Broadwell-U Integrated Graphics
>        vendor: Intel Corporation
>        physical id: 2
>        bus info: pci@0000:00:02.0
>        version: 08
>        width: 64 bits
>        clock: 33MHz
>        capabilities: msi pm vga_controller bus_master cap_list rom
>        configuration: driver=i915 latency=0
>        resources: irq:43 memory:e0000000-e0ffffff memory:d0000000-dfffffff
> ioport:1800(size=64)
> 
> a@chrome:~$ uname -a
> Linux chrome 4.2.0-19-generic #23-Ubuntu SMP Wed Nov 11 11:39:30 UTC 2015
> x86_64 x86_64 x86_64 GNU/Linux
> 
> But today display was blanked after 15 minutes of inactivity and when I
> woken it up I saw no more flickering and this kernel message:
> Dec  5 10:16:48 chrome kernel: [ 3708.390613] [drm:intel_dp_start_link_train
> [i915]] *ERROR* failed to enable link training
> 
> please suggest a way (usingn a kernel parameter) to disable link training
> until a bugfix is backported

I need to add some additional info. Ive managed to reproduce the case when after screen blanking there's no flickering anymore. I start the 'xset dpms force off' command to blank the screen and after a pause I press a button to wake it up. Below is a pastebin when flickering persist after waking up:
http://pastebin.com/fuY57tMH

And here is a pastebin when the flickering is gone after waking up:
http://pastebin.com/4gGMTycL

It was really difficult to reproduce the case when the flicker is gone

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/47

------------------------------------------------------------------------
On 2015-12-06T10:03:02+00:00 Furniss-tom wrote:

Just wanted to summarise the progress against the original problem,
which may or may not be related to some of these other issues, and to
add some test detail.

The original problem was a continually flickering screen, starting part-
way through boot and prior to the login screen, and affected the
extended display port of the laptop screen only, not external monitors.

Mika's original patch fixed this issue, removing the flicker, but during
QA Mika was asked to modify it to remove kernel parameters.  Mika's
revised (second) patch also resolved the issue.

With both of Mika's patches there were still some graphics issues:
1) Initial blank screen on boot.
2) Occasional blinking of the graphics, ranging from every few seconds to every 2-3 minutes.  The blink lasted only a fraction of a second, and whilst noticeable it wasn't a major concern.
3) The flickering returned when resuming from sleep.

Issue 1 was a relatively common brightness issue, and was resolved by
using kernel parameter acpi_osi=linux, and running this command
automatically on startup, "setpci -s 00:02.0 F4.B=00".  This also
resolved issue 2, removing the occasional blink.

Issue 3 remains.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/48

------------------------------------------------------------------------
On 2015-12-06T16:26:36+00:00 Oscar Morante wrote:

I applied the latest patch from Mika on top of drm-intel-nightly and
it's been working great for the last couple of days.  Suspending or
changing resolution doesn't cause flicker anymore, and it also seems to
have fixed the ocassional one frame blackout I had before (which still
happens on windows btw).

I didn't need any extra configuration like Tom, it just worked out of
the box.  I'll let you know if something changes but it seems to be
fixed on my system.

Thanks!

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/49

------------------------------------------------------------------------
On 2015-12-07T14:15:25+00:00 Mika-kahola wrote:

(In reply to Oscar Morante from comment #46)
> I applied the latest patch from Mika on top of drm-intel-nightly and it's
> been working great for the last couple of days.  Suspending or changing
> resolution doesn't cause flicker anymore, and it also seems to have fixed
> the ocassional one frame blackout I had before (which still happens on
> windows btw).
> 
> I didn't need any extra configuration like Tom, it just worked out of the
> box.  I'll let you know if something changes but it seems to be fixed on my
> system.
> 
> Thanks!

Great to hear that the patch worked out for you!

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/50

------------------------------------------------------------------------
On 2015-12-07T15:00:12+00:00 Mika-kahola wrote:

Created attachment 120389
Check if DP training set applied ok

Tom reported that flickering occurs when resuming back from the sleep.
When resuming we are already trained the DP link and most probably
reusing the DP link parameters when retraining the link. It may be
possible that setting the DP training pattern fails yielding an error
message of "*ERROR* failed to enable link training". This patch
introduces a check to the routine that applies the DP training pattern.
If this check fails, the link training is restarted by setting the
parameters to zero.

The patch applies on top of the latest drm-intel-nightly and requires
this https://patchwork.freedesktop.org/patch/66697/ patch to be applied

Reply at:
https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1522922/comments/51


** Changed in: nouveau
       Status: Unknown => Incomplete

** Changed in: nouveau
   Importance: Unknown => Medium

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https://bugs.launchpad.net/bugs/1522922

Title:
  Screen flickering in Intel i915 driver

Status in Nouveau Xorg driver:
  Incomplete
Status in libdrm package in Ubuntu:
  Confirmed

Bug description:
  There's an upstream bug reported here
  https://bugs.freedesktop.org/show_bug.cgi?id=91393 that causes screen
  flickering when using the Intel i915 builtin driver (at resolutions
  lower than the maximal one).

  I think that it will be fixed in newer kernel versions, but for the
  time being, as reported here
  https://bugs.freedesktop.org/show_bug.cgi?id=91393#c25 (and as
  personally tested) reverting those two commits fixes the problem.

  Would that be possible to release a fixed version for the 4.2.0
  stream?

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-4.2.0-19-generic 4.2.0-19.23
  ProcVersionSignature: Ubuntu 4.2.0-19.23-generic 4.2.6
  Uname: Linux 4.2.0-19-generic x86_64
  ApportVersion: 2.19.1-0ubuntu5
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  bettini    1378 F.... pulseaudio
   /dev/snd/controlC1:  bettini    1378 F.... pulseaudio
  CurrentDesktop: KDE
  Date: Fri Dec  4 19:01:00 2015
  HibernationDevice: RESUME=UUID=7ddbc972-3ad6-40de-9313-2bb9395145f9
  InstallationDate: Installed on 2015-05-08 (210 days ago)
  InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
  MachineType: Dell Inc. Dell Precision M3800
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-19-generic root=UUID=dd2c7064-53b9-4720-96ab-5e8a3f2db3ea ro noprompt quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-19-generic N/A
   linux-backports-modules-4.2.0-19-generic  N/A
   linux-firmware                            1.149.3
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: Upgraded to wily on 2015-11-07 (26 days ago)
  dmi.bios.date: 08/17/2015
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A10
  dmi.board.name: Dell Precision M3800
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A10
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.chassis.version: Not Specified
  dmi.modalias: dmi:bvnDellInc.:bvrA10:bd08/17/2015:svnDellInc.:pnDellPrecisionM3800:pvrA10:rvnDellInc.:rnDellPrecisionM3800:rvrA10:cvnDellInc.:ct8:cvrNotSpecified:
  dmi.product.name: Dell Precision M3800
  dmi.product.version: A10
  dmi.sys.vendor: Dell Inc.

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