https://bugs.freedesktop.org/show_bug.cgi?id=107154
--- Comment #1 from dwagner jb5sgc1n.nya@20mm.eu --- Indeed, crashes upon S3 resumes have been abundant with amdgpu.dc=1 for many months now, and seemingly for more than one reason.
One bug I reported in August 2017 with https://bugs.freedesktop.org/show_bug.cgi?id=102323 - that one was fixed quickly.
The next S3 resume crash I reported in October 2017 in https://bugs.freedesktop.org/show_bug.cgi?id=103277, that one stayed without any resolution until April 2018, and the fix found in that report only works if no "drm.edid_firmware=..." kernel command line option is used.
Another crash bug with S3 resumes I reported for 4.17.2 kernels in https://bugs.freedesktop.org/show_bug.cgi?id=107065 - then realized that 4.18 pre-releases exhibit the very same kind of crash immediately upon starting X11. For this crash upon X11 startup, there is a patch in the bug report, but it does not prevent the S3 resume crash.
I currently work around S3 resume crashes by switching to the console display before enterin S3 sleep - but this is really an awkward work-around.