I recently obtained this monitor and running it on Debian via an AMD R9 Fury. When I try to set the monitor at 1920 x 1080 @ 240 Hz it will show distortion on the right side of the screen, and the screen reports to be running at 1920 x 1080 @ 241 Hz via the Information section of the monitor's OSD. This does not happen on Windows. I have tested this on Debian stable, Debian testing and Ubuntu 17.10, with all expressing the same result. The value is 239.76, yet when I switch to it, the monitor will report 241 Hz, which most likely causes the screen distortion. user@fdt:~$ xrandr Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384 DisplayPort-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 544mm x 303mm 1920x1080 60.00 + 239.76 143.98* 119.98 99.93 50.00 59.94 1920x1080i 60.00 50.00 59.94 1680x1050 59.95 1600x900 60.00 1280x1024 239.77 120.05 75.02 60.02 1280x800 59.81 1152x864 75.00 1280x720 60.00 50.00 59.94 1024x768 75.03 60.00 832x624 74.55 800x600 75.00 60.32 720x576 50.00 720x480 60.00 59.94 640x480 75.00 60.00 59.94 720x400 70.08 DisplayPort-1 disconnected (normal left inverted right x axis y axis) DisplayPort-2 disconnected (normal left inverted right x axis y axis) HDMI-A-0 disconnected (normal left inverted right x axis y axis) DVI-D-0 disconnected (normal left inverted right x axis y axis)
Created attachment 136802 [details] 240 Hz right side screen distortion picture
Created attachment 136803 [details] 240 Hz right side screen distortion video
This is probably a display driver bug, not a Mesa bug. Please provide your kernel version and dmesg output.
Created attachment 136806 [details] dmesg
I have installed Ubuntu 16.04 so I could try this with AMDGPU-PRO. The 240 Hz distortion still occurs.
Tested this with my on-board Intel graphics capabilities. The issue does not occur. It seems to be isolated to AMD graphics.
With the help of hwentlan @ irc.freenode.net #radeon I was able to obtain a solution. Using kernel 4.15 RC9 on Ubuntu 16.04 and booting with the amdgpu.dc=1 kernel option, the issue no longer occurs. This toggle indicates the use of the new amdgpu driver. So one can assume that this is fixed as of 4.15 and when that toggle becomes standard.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.