[SOLVED] - Problem, Possible Xorg issue for my rig that uses MST on 1

I recently bought x6 ASUS 24inch monitors for my battle station and I’m having a tad bit of an issue setting up the MST Hub to get the extra 3 working.

I’m entirely new to xorg configurations, and i have a unique case here, any help would be much appreciated. In ubuntu 16.04 with AMD GPU Pro drivers running on a RX 580 8GB. 1 HDMI + 2 DP (3 monitors without hub) works fine. Plug in the Hub into the 3rd DP nothing in the MST Hub. it still runs fine.

Plug a HDMI to DP cable from the monitor to the hub for the remaining 3 monitors. As soon as i plug the first monitor in it detects it, but only allows 1024×768, also unknown is named on it and does not display anyout put on the monitor. Also it lags / locks up for a good minute.Plug in another monitor and it just craps out to black screen. Did a variation of boots with all of them plugged into the MST HUB, and so on. No joy.

Any ideas? Also thank you for your time.

MST HUB: http://club-3d.com/en/detail/2434/

Update: using fedora 27 hub is recognized and now mirroring but not extending so at least getting further.

[SOLVED] - Replaced OS with Fedora 27, since it has multi GPU Support Using the old AMD GPU i previously had with the new one for the last 6th Montior (5 on Rx 580 1 on R9 280X) for my x6 Monitor setup.

Problems: R9 280X - x1 monitor some times artifacts and requires countless relog’s to correct the display.

Update: Still having issues. Has anyone ever had these problems? @wendell Probably the only person I know with lots of monitors setup, hopefully one day he has some spare time to check this lol.

MST Hub, Dmesg states [drm:amdgpu_dm_connector_mode_valid [amdgpu]] ERROR dc_sink is NULL! and the monitor isn’t detected on the hub so all the settings revert to like unknown.

GPU Plugged in with: x2 end DP slots and a HDMI for x3 Monitors WITHOUT Hub.
Hub is plugged into the first DP Slot, with 1 Monitor being detected but sink name isn’t.

Here’s the log: https://pastebin.com/rQSEUbzC

It’s a real shame Xorg is so broken for multi monitor that it does not allow multiple displays over multiple GPUs. Hoping Wayland fixes this. Have you tried GNOME with native Wayland? Fedora defaults to Wayland GNOME.

No haven’t really tried any other environments yet. Been hoping to get this working with ubuntu/cinnamon. I’ll have to give Fedora a shot.

This setup ive got going from all one GPU with a MST Hub tho. I can get it working no problems in windows. But who the hell wants that?

Yeah, Cinnamon is still pretty tied to Xorg. KDE and GNOME are slowly moving towards Wayland, but only GNOME defaults to Wayland on some default flavors of some distros.

So Ubuntu 17.10 is wayland from what im reading is default. Might have to test it out.

The live image is Xwayland. Make sure it’s native Wayland and not Xwayland.

Ah, good call.

Fedora 27 Workstation Downloading at the moment.

Well, its fully installed on Fedora 27, Good news so far is it detected the Monitor plugged into the MST, But only one and it mirrored the displays.

So I need to find some opensource AMD GPU Drivers for RX 580 that supports the MST Hub. I dont game on this box so as long as I can get the multi monitors working thats all that matters.

If you know any drivers let me know, thx again.

Aha, so Wayland did make a difference! Hopefully the Radeon open source drivers will support that cause I know there’s a big community of people writing code for that. Maybe request it as a feature?

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Might have to, you know the github of any active opensource amdgpu repos? Unless Mesa request will do it.

You might try stepping down the res or refresh rate. Similar symptoms can occur from dodgy cables.

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Not sure if that would work if it works fine on windows 10 with all 6 monitors. But I guess wouldnt hurt to try, I’ve put as many monitors on the GPU i can get the MST hub down to only 2. With DVI on GPU.

id start off trying out ‘xrandr -q’ and see if your GPU even see there is 6 monitors.

You could see about getting a RX 560 cause Multi-GPU Wayland works with Fedora out of the box. That’s something impossible on Xsserver.

Posting to indicate I’m having a similar issue with MST on Fedora 27 (X11).

2x Dell monitors (U2415H), DP MST on a 580. Fully updated kernel. In this situation, the output is mirrored on both monitors.

Yeah, that’s what my MST hub does too. Also on fedora 27.

I previously had ubuntu, which didn’t recognize the hub at all or any monitors connected to it. At least with fedora it recognizes the other monitors and displays. Just wish it extended not mirrored.

Do you think I assume you mean in crossfire? I only have a 280x spare atm I guess I could pickup a 560, but then again I bought this MST HUB to do what the extra card would do… but prob be my last resort.

Tho, on second hand another gpu could help with lag with so many monitors. Anyone know the ram usage per monitor on average?

The 560 would be more energy efficient, but I’m not talking about Crossfire, I’m only talking about having a second low power GPU with enough ports to satisfy the rest of your monitors, and it looks like with Wayland, they finally fixed multiple displays over multiple GPUs, something impossible with Xorg.

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