(In reply to mikita.lipski@amd.com from comment #19)
> I have attempted to reproduce an issue, but didn't succeed.
> We have used an identical hardware setup with a reference rx460 card and
> couldn't reproduce a hang on various kernel versions.

Strange. If I didn't keep an older amd-staging-drm-next kernel from October
2017 in use where S3 resumes work every time, I would doubt my hardware - but
the way it is the only possible cause is a kernel change sine then.

> There is still a possibility that some kernel config options might be
> causing an issue. 
> If its possible, could you please provide kernel configuration so the
> testing environment is identical.

Sure, will attach my .config (as used with the current drm-next-4.17-wip) after
this comment.

> Also does the issue reproduce reproduce if you disable DC? (amdgpu.dc=0 in
> GRUB menu)

Tested with today's drm-next-4.17-wip git: With "amdgpu.dc=0" on the kernel
command line, resume from S3 works fine for me, both from the console (before
starting X11) and when running X11.
(But of course, no 4k/60Hz video and no HDMI audio with amdgpu.dc=0, so that is
not really an option for actual use.)

So the resume-from-S3 failures are definitely caused by something in the DC
code that changed since early October 2017.