I'm having some issues with my A409U running off a R9 380 through displayport.
When I plug the monitor in through HDMI, it's working fine, but limited to 24hz.
The monitor, through DP (3840x2160@60), seems to work fine in Windows, if I set 8 BPC. Not sure if that's relevant.
In linux, it's not the monitor that's causing an issue, it's more of the GPU drivers (amdgpu on Arch x64, kernel 4.5) There were kernel messages that I saw last night:
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed: 5 tries
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed
When I have it plugged in through DP, xrandr
reports that it's trying to display at [email protected], however I get a no signal notice on the display.
When I'm looking in the cinnamon-settings display window, the kernel spits out the following:
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed: 5 tries
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed: 5 tries
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* channel eq failed
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* displayport link status failed
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* clock recovery failed
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* displayport link status failed
[drm:amdgpu_atombios_dp_link_train [amdgpu]] *ERROR* clock recovery failed
I've also got a GTX 660 ti that has displayport, and according to the nvidia website, it's supposed to have DP1.2, however, I haven't tried it yet.
Any ideas?
EDIT: So it seems like the AMD drivers are entirely at fault here. For anyone else encountering these issues, if you have an available Nvidia card (mine is a gtx 660 ti) that supports 4k@60, give it a try with the proprietary drivers and see if that works. Hopefully the kernel devs will be able to get these issues sorted soon.