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Filed from caserun (https://tcms.engineering.redhat.com/run/260129/#caserun_10820272)

Version-Release number of selected component (if applicable):
RHEL-7.2-20150820.0
xorg-x11-server-Xorg-1.17.2-7.el7.x86_64
xorg-x11-drv-ati-7.5.0-3.el7.x86_64
kernel-3.10.0-306.0.1.el7.x86_64
linux-firmware-20150727-41.git75cc3ef.el7.noarch
mesa-dri-drivers-10.6.0-1.20150616.el7.x86_64

Steps to Reproduce: 
obtain a box with DP output  and as much screens as can be attached


 1. connect screens through DP port
 2. perform suspend/resume cycle two times



Actual results: 
If machine booted without DP, hotplugging will cause it to reboot immediately.
Otherwise (if booted with DP plugged in) DP works, but repeated hotpluging with 3+ monitors will cause it to stop working (xrandr will show DP monitor as working, but the monitor will go to sleep from lack of signal).


Expected results:
Screens should be correctly set, their native resolution should be set and
suspend/resume cycles should work as well


Additional info:
DP also suffers from mild temporary corruption on wake from standby - same as every digital output on this video card, this is a separate bug: https://bugzilla.redhat.com/show_bug.cgi?id=1263784

So talked with Vasiliy and we believe this was some electrical grounding issue on his test setup. We could not reproduce on mine.