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fm4d

Member

Registered: 2016-04-08

Posts: 6

[SOLVED] Graphical glitches with daisy-chained external monitors

Hello, I have Dell XPS 13 (9343) and 2x Dell U2414H. I daisy-chained them, enabled DP1.2 on first monitor, made sure that I have up-to-date kernel and xf86-video-intel etc. and I experience strage graphical gitch when the second external monitor with a random frequency (sometimes 1 per minute, sometimes 1 per 3 seconds) 'shifts' the bottom part of the image to the right and back so it looks like a really fast wave and this sometimes also occurs on the first external monitor, but rarely. Also the second monitor in the chain sometimes goes black for few seconds.

What I tried:
- changing cables
- changing the order of monitors
- Option "AccelMethod" "uxa" in intel config
- Option "TearFree" "true" in intel config
- Option "NoAccel" "True" in intel config
- installing xf86-video-intel git version

and more stuff that I found with no results. The only thing that helps is to use lower resolution on second monitor (1600x900 for example) as described in this bug report - https://bugs.launchpad.net/dell-sputnik/+bug/1487036 but it is 6 moths old with no activity and having different resolution between those monitors is really killing my eyes. Any tips? Thanks.

Last edited by fm4d (2016-04-11 16:22:42)

fm4d

Member

Registered: 2016-04-08

Posts: 6

Re: [SOLVED] Graphical glitches with daisy-chained external monitors

UPDATE:

After trying everything possible I tried to switch from xf86-video-intel tot xf86-video-modesetting with some interesting results.
Xrandr is now working much faster, before it took about 5+ seconds to setup monitors with xrandr, now it is about 1 second.
The graphical glitches are pretty much gone BUT I experience really weird stuff with mouse. Moving mouse between monitors
cause black screens for long periods of time and sometimes even permanently. Any hints how to deal with it?

fm4d

Member

Registered: 2016-04-08

Posts: 6

Re: [SOLVED] Graphical glitches with daisy-chained external monitors

linux-lts fixed it, I could try that earlier.. :X

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: [SOLVED] Graphical glitches with daisy-chained external monitors

Using linux-lts is not a fix, eventually the version used for linux-lts will be more recent and you will have the same problem again. You should try to narrow down the version where this started to happen and if possible try to bisect the kernel and submit a bug upstream. At least narrow it down to which is the first kernel version with problems and report that (read: submit a bug) upstream.

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R00KIE
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