Bug 103364 - Black Screen Flickering
Summary: Black Screen Flickering
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: XOrg git
Hardware: x86-64 (AMD64) Linux (All)
: high normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
Whiteboard: ReadyForDev
Depends on:
Reported: 2017-10-19 20:03 UTC by Wolfgang Haupt
Modified: 2019-02-04 18:16 UTC (History)
5 users (show)

See Also:
i915 platform: KBL
i915 features: display/LSPCON

dmesg (184.17 KB, text/plain)
2017-10-19 20:03 UTC, Wolfgang Haupt
no flags Details
YUV 4:2:0 dmesg (119.56 KB, text/plain)
2017-11-10 19:19 UTC, Wolfgang Haupt
no flags Details
displayinfo (8.87 KB, text/plain)
2018-04-26 15:13 UTC, Wolfgang Haupt
no flags Details
edid-decode (6.08 KB, text/plain)
2018-05-06 20:24 UTC, Wolfgang Haupt
no flags Details
EDID binary (256 bytes, application/octet-stream)
2018-05-07 19:19 UTC, Wolfgang Haupt
no flags Details
lg hex (1.24 KB, text/plain)
2018-05-07 19:19 UTC, Wolfgang Haupt
no flags Details

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Description Wolfgang Haupt 2017-10-19 20:03:12 UTC
Created attachment 134928 [details]

When I choose 3180x2160_60Hz my TV starts to blink/flicker black.
The black screen shows about 1-2sec.
Unfortunately at the time the flicker happens, there is no indication in dmesg.

uname -a:
Linux lrplayer 4.14.0-rc4 #1 SMP Tue Oct 10 21:53:48 CEST 2017 x86_64 GNU/Linux

Linux Distribution:

Intel NUC7i5BNK
Comment 1 Wolfgang Haupt 2017-10-19 20:06:02 UTC
I tried to attach the video that shows the issue, but it failed.
So here is my dropbox link:
Comment 2 Wolfgang Haupt 2017-11-10 19:19:07 UTC
I did some investigation and it seems to be a bandwith issue.
I've rebased following patch series on current (todays) drm-tip:

You can find the branch here: (I applied the patches with std patch, so I lost author information, I added the original author with the signed-off tag, not sure if this is the right thing to do, it's only for discussion anyway)

It didn't work out and my system never switched to 4:2:0 until I tried this commit:

According to my dmesg output something seems wrong, though (yuv420_dmesg.log).
But this fixes the blackscreen flickering.

I'd really like to see progress with this yuv 4:2:0 mode as it seems to fix a big issue for many Intel NUC users that want to use it as a HTPC and have a GUI running in 4k@60.
Comment 3 Wolfgang Haupt 2017-11-10 19:19:41 UTC
Created attachment 135379 [details]
YUV 4:2:0 dmesg
Comment 4 Jani Saarinen 2018-03-29 07:11:43 UTC
First of all. Sorry about spam.
This is mass update for our bugs. 

Sorry if you feel this annoying but with this trying to understand if bug still valid or not.
If bug investigation still in progress, please ignore this and I apologize!

If you think this is not anymore valid, please comment to the bug that can be closed.
If you haven't tested with our latest pre-upstream tree(drm-tip), can you do that also to see if issue is valid there still and if you cannot see issue there, please comment to the bug.
Comment 5 Wolfgang Haupt 2018-04-04 14:32:12 UTC
This is still relevant.
I've tested with drm-tip recently and it is still the case.
Comment 6 Jani Saarinen 2018-04-04 15:37:50 UTC
so you are expecting series of: https://patchwork.freedesktop.org/series/36068/ to land to drm-tip?
Comment 7 Wolfgang Haupt 2018-04-04 15:49:28 UTC
At least this seems to fix the black screen flickering for me (tried to explain it in my early comments on this issue).
However I don't know if anyone can answer why 4k@60 doesn't work with YUV 4:4:4.
Comment 8 Ville Syrjala 2018-04-04 16:02:37 UTC
(In reply to Wolfgang Haupt from comment #7)
> At least this seems to fix the black screen flickering for me (tried to
> explain it in my early comments on this issue).
> However I don't know if anyone can answer why 4k@60 doesn't work with YUV
> 4:4:4.

The usual suspect is the cable, connectors, dongles etc.
Comment 9 shashank.sharma@intel.com 2018-04-04 16:03:45 UTC
Even though this series provides the infrastructure for YCBCR444, there is no interface for user (like a drm_property) to select its preference of YCBCR444 over RGB. We had tried to add this property during HDMI 2.0 enabling but we realized that it was not mapping to the long term goal of HDR pipeline support. So, to summarize, modeset picks RGB output by default.

In case of LSPCON based YCBCR 4:2:0 outputs, we run pipe at YCBCR 4:4:4 config, and then LSPCON scales it down to 4:2:0 sub-sampling, and that's where we need the infrastructure.

So in order to support YCBCR 4:4:4 outputs, we need a drm_property which picks user's preference between RGB/YCBCR444. 

- Shashank
Comment 10 Wolfgang Haupt 2018-04-04 16:07:09 UTC
Sorry maybe I'm not aware of all the technical aspects, if you say normal behaviour is RGB444, then this means my problem is actually black screen flickering with RGB444 as well.
Comment 11 Wolfgang Haupt 2018-04-04 16:09:06 UTC
Please note that I tried cables of 3 different manufacturers and I don't use any dongles.
My NUC is directly connected to the TV and there's several people that have this issue with kaby lake NUC's.
Comment 12 Jani Saarinen 2018-04-25 08:18:52 UTC
What is your version of LSPCON FW? 
Can you provide: cat /sys/kernel/debug/dri/0/i915_display_info
Comment 13 Wolfgang Haupt 2018-04-26 15:13:03 UTC
I'm on lspcon 1.72
Comment 14 Wolfgang Haupt 2018-04-26 15:13:34 UTC
Created attachment 139137 [details]
Comment 15 Jani Saarinen 2018-05-04 09:54:15 UTC
Jani, Shashank, Ville. Any help here?
Comment 16 shashank.sharma@intel.com 2018-05-04 17:12:59 UTC
Would it be possible to share the monitor's edid in text format ?

- Shashank
Comment 17 Wolfgang Haupt 2018-05-06 20:24:44 UTC
Created attachment 139400 [details]
Comment 18 Ville Syrjala 2018-05-07 12:25:42 UTC
(In reply to Wolfgang Haupt from comment #17)
> Created attachment 139400 [details]
> edid-decode

Always raw binary/hex please. We don't want to be at the mercy of the decode tool as those may have bugs or missing features.
Comment 19 Wolfgang Haupt 2018-05-07 19:19:03 UTC
Created attachment 139409 [details]
EDID binary
Comment 20 Wolfgang Haupt 2018-05-07 19:19:33 UTC
Created attachment 139410 [details]
lg hex
Comment 21 Martin Peres 2018-07-17 14:10:43 UTC
Ville, Shashank, could you have a look at Wolfgang's EDID?
Comment 22 Swati Sharma 2018-12-04 14:20:42 UTC
Hi Wolfgang Haupt,

Can you please update the MCA fw to 1.75, you are still using the older version? 

Since YCBCR 420/444 series is recently merged https://patchwork.freedesktop.org/series/50897/ this issue shouldn't be there. 

Even if the issue persists with latest kernel and after updating the fw, we will take next steps.

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