Created attachment 94377 [details]
tar file containing /var/log/Xorg.0.log and logs of dmesg, xrandr, xrandr --verbose for both cards (r7-240 and r7-250)
The XFX Radeon r7-240a-clh4 and XFX Radeon r7-250a-zlh4 video cards do not seem to be able to generate 3840x2160 @ 30 Hz video modes over HDMI, even though I believe their hardware is supposed to be capable of this (~299 MHz pixel clock).
At least with my se39uy04 39" Seiki television, the Radeon X.org driver happily passed through the five 3840x2160 @ 24-30 Hz that the television's advertises in its EDID modes to xrandr, meaning that driver thinks it can support those video modes, but, if I select any of them, the telvision just says "mode not support." In comparison, if I make a custom video mode for 3840x2160 @ 15Hz, the 4k TV displays that fine.
I am attaching a .tar.gz file containting /var/log/Xorg.0.log and logs of dmesg, xrandr, xrandr --verbose for both cards (r7-240 and r7-250).
Thanks to Alex Deucher for advising me to file this bug report here.
Thanks in advance for any further processing of this bug report.
Created attachment 95261 [details] [review]
Does the attached patch help?
I confirm that applying your patch to linux-3.13.0 resulted in both XFX Radeon video cards working (r7-240a-clh4 and r7-250a-zlh4).
Thank you, Alex! Great work!
Just to clarify, I confirm that that patch made both video cards successfully output 3840x2160 over HDMI to a Seiki se39uy04 television.
Great. Patch is sent upstream and should show up in the stable series as well soon.