R290x combined with Mg279q, Dp link fail in ubuntu-multihead setup.
Assigned to Default DRI bug account
Epuigpment: CPU Amd fx8350, Mboard: Gigabyte GA-990FXA-UD3, Ram 16 gb. Sapphire R9 290x.
Monitor setup: 2 monitors, 1 right side (DP-0) Asus MG279q, 1 left(HDMI-0)pb279. Both are 1440p monitors, with the Mq279q have high refreshrate 144hz.
Using randr for multihead.
OS: Ubuntu 16.04, kernel 4.4.0-31-generic
Problem: The right screen is blank, as long as I try to use standard resolution, meaning 1440p. Can only get it to work in 1080p, at 60hz. It worked perfectly in the old fgrlx when running ubuntu 14.4, and with radeon in ubuntu 14.4, though it might have been both screens at 60hz with the radeon driver.
When trying with livecd's, the fedora 24 is working at 1440p at 60 hz, but fails if i try to increase the refresh rate.
Ubuntu live 16.04, fails the same way as my install.
I think its releated to the radeon driver, but i cant be sure.