Dual Link DVI not detected with Debian 10

[waldo22]

I recently upgraded 2 separate machines from Stretch to Buster and neither of them properly detect Dual-link DVI in the Mate Desktop Environment (haven't tested others yet).

Both are using 2560x1600 30" Dell monitors, one from 2008 and one from 2014, and both worked properly at 2560x1600 under Stretch.

A 3rd machine with the same 2008 model monitor works properly at 2560x1600 under Buster when connected via DisplayPort.

Any idea what may have changed, and tips on a temporary fix?

I tried adding a custom modeline and that didn't work.

[Head_on_a_Stick]

I tried adding a custom modeline and that didn't work.

You should post exactly what you tried, maybe you did it wrong.

What is your graphics hardware and drivers?

Code: Select all

lspci -knn | grep -iA2 'vga\|display\|3d'

[waldo22]

Using the Kernel i915 driver:

Code: Select all

00:02.0 VGA compatible controller [0300]: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller [8086:0152] (rev 09)
Subsystem: ASRock Incorporation Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller [1849:0152]
Kernel driver in use: i915

I used CVT and xrandr with this guide:
https://medium.com/devsys/adding-a-new- ... a08d73f327

The GUI display tool still only allows me to select up to 1920x1200, which indicates single-link DVI.

Bigger question is why did this work fine on both machines under Stretch but now doesn't work in Buster?

I literally was running at 2560x1600, did an `apt dist-upgrade` and now I can only get 1920x1200.

[waldo22]

Important detail I left out (sorry):
Intel graphics doesn't support dual-link DVI; the machine in question is using an active (powered) mini-DP to dual-link DVI adapter.

The issue still stands that the proper EDID and resolution were detected on Stretch but not Buster after upgrading the exact same machine.

[Head_on_a_Stick]

Check the X.Org log (or inxi) and see which DDX driver is being used. If it's the modesetting driver then try switching back to Intel's version: https://wiki.archlinux.org/index.php/In ... figuration

It's a bit of a stab in the dark but it's all I can think of atm. Perhaps somebody else will do better.