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#1 2021-09-25 03:56:20

sokol99
Member
Registered: 2021-09-25
Posts: 13

[Solved] Blinking screen -- static?

Hi, I have been wrestling with my 'personal' linux (now Arch) computer in my office for nearly two years and have been trying different ways to try to identify the source of a sporadic blinking screen.

The box is a converted Chromebox CN62 connected via HDMI to a KVMed 34" LG monitor running in split screen mode. (Would an odd resolution do this?).   Hence it is an intel HD Graphics 5500.  The other input into the monitor is a DP feed from my Windows work laptop.  That half never blinks. Only the HDMI side and almost exclusively  when displaying the Arch box feed (though not exclusively).  I have the same issue if I bypass the KVM.

... I have discovered I can *force* a blink (generally only on that half of the monitor) via static but have tried static-focused solutions such as running a humidifier and grounding my chair mat.  But I still get inexplicable blinking. ... I have previously tried another 34" split monitor but dropped that when I discovered I could cause some blinking with static.   I even brought my monitor in to be looked at.  Nothing there.

I followed the guide in terms of installing the recommended drivers: mesa, xf86-video-intel, vulkan-intel as well as the microcode at installation time.  Both my Arch install and the previous mint 19.3 install had this issue.

I would like to find a way to definitively identify the source of the blink and am wondering if there are any clues to be had from the box itself?  I have attempted use of drm.debug and dmesg but find nothing of note when I look at the logs immediately after these blinks.

..I'm going crazy and am hoping someone can offer some insight or strategy to take that can help me finally figure this problem out!

Please!?

Thanks,
sokol99

Last edited by sokol99 (2021-10-27 19:09:40)

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#2 2021-09-25 04:03:00

Trilby
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Registered: 2011-11-29
Posts: 25,913
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Re: [Solved] Blinking screen -- static?

sokol99 wrote:

I followed the guide in terms of installing the recommended drivers: ... xf86-video-intel

Which guide recommended that?  That driver has been problematic for a while and gets worse by the day.  A vast majority of intel graphics systems will be better without it.  Your symptoms don't match any described symptoms of xf86-video-intel problems that I'm aware of, but it does cause a wide range of issues - so it'd be worth testing without it before looking much further.


"UNIX is simple and coherent..." - Dennis Ritchie, "GNU's Not UNIX" -  Richard Stallman

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#3 2021-09-25 04:05:02

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

I was following the wiki here: https://wiki.archlinux.org/title/Intel_graphics

Are you recommending I remove just that driver?  I would I need to proactively install an alt to test that approach out?  (as my screen just blinked again). smile

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#4 2021-09-25 04:16:29

sokol99
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Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Ok, removed just that package and rebooted.  Will watch for a bit.

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#5 2021-09-25 04:27:32

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Nope.  Still blinking. ... hmm

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#6 2021-09-25 07:14:10

seth
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Registered: 2012-09-03
Posts: 25,137

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#7 2021-09-25 13:43:36

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Thank you, I will try that next. One note is that when the screen does "blink" it is usually blank for a second or several seconds.  It's not a really fast blip but something I have to wait to finish before I can resume working...

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#8 2021-09-25 14:33:04

seth
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Registered: 2012-09-03
Posts: 25,137

Re: [Solved] Blinking screen -- static?

Only the HDMI side and almost exclusively  when displaying the Arch box feed

Wonky cable causing a re-connect?

xrandr --output HDMI-whatever --set audio off

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#9 2021-09-25 16:14:50

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

I have tried different cables including just the other day as I again bypassed the VPN.  But, I am not using the HDMI audio so I suppose it wont hurt to try that as well. Maybe decrease the 'noise'?   Thanks!

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#10 2021-09-27 18:33:56

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Problem persists after making the recommended changes above.  I toggled over from work computer and immediately had 'blinking' screen.  One lasted upwards of 3 seconds.  No logs of interest with debug on..  just a bunch of entries like so .
kernel: [drm:drm_mode_addfb2 [drm]] [FB:95]

I toggled back to my work HDMI feed (on that half of the monitor) and no blinking.  I come back and another blink.  I think that helps point to it NOT being static I hope.  But what?  Are there additional logs I could turn on?

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#11 2021-09-27 19:34:38

seth
Member
Registered: 2012-09-03
Posts: 25,137

Re: [Solved] Blinking screen -- static?

If you can force the symptom through Electrostatics but cannot prevent it by shielding, it's likely *some* issue with the signal.
https://www.asus.com/Displays-Desktops/ … /techspec/ says the thing has a DP output, can you cause the issue when flipping the cables? Or does it maybe reverse and the windows system starts to flicker?

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#12 2021-09-28 15:24:50

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Thanks seth, that's a great idea.  I had not specifically tried that.  Meaning cause a blink via static when using the DP port.     

What I had done is use that DP port with an active converter to HDMI because I felt it blinked less than the direct HDMI port (with Ubuntu).  But I have had blinking with that port as well when used as described.  I have never tested it with outright DP for blinking. So I will try that.

It also gives me an idea to try a DP KVM and use primarily DP vs HDMI in my set up.  I will also plan on trying that.  ..One minor issue I've noticed with the DP port is that I don't get the bios / grub screen...  (Edit.  Bios/Grub does display when directly connecting via DP)

I will let you know. Thanks!

Last edited by sokol99 (2021-09-28 16:39:31)

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#13 2021-10-27 19:06:57

sokol99
Member
Registered: 2021-09-25
Posts: 13

Re: [Solved] Blinking screen -- static?

Hi All,

I'm going to mark this issue as "Solved" now. 

In short, I believe I have had a combination of some static issues impacting my HDMI connections as well as "EDID" issues growing out of using my 34" monitor in PBP mode. 

In order to address potential static issues I've switched to using a DP vs an HDMI kvm switch and have added additional grounding to my workstation.  (Both my mat and desk share common grounding with an outlet now.)

In transitioning to a DP based KVM my EDID issue was additionally complicated because most DP kvm's do not 'maintain' the video connection to the computer when switching inputs.  (Apparently that's supposed to be a DP-managed thing but it wasn't working for me.) 

After looking around I did find a handful of rather expensive kvms that do support DP EDID "DDM" and "DDC" connection maintaining.  ...But, event then, I discovered that my PBP mode was going to be 'confusing' to the kvm anyway. 

So, in the end I stuck with a basic 2-port DP kvm and found this device to maintain the DP connection to the monitor independently of the kvm.   Seems to work great.

https://www.kvmgalore.com/shopping/nti- … 52481.html

I now have a stable, toggle-able connection. Sanity (partially) restored. smile

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