Thank you Magic Banana for suggestion. I don't think that using an old kernel
is a very wise idea, although I've tried it. However as you would expect it
gave me bunch of errors and did not mount the /home directory properly. The
boot process dropped me into a terminal (recovery mode). I started X from
there, but there was no option to suspend computer at all. And strangely, the
graphics also didn't work well, I got VESA driver again.
Booted back to original kernel then. I tried changing sleep modes in
/lib/systemd/system/systemd.suspend.service and I have tried suspend
(original), hybrid-sleep and hibernate modes - all of these failed the same.
The computer actually suspends in suspend mode, power led changes from green
to orange. When I push the power button it changes the color again, the
cooler starts spinning, but there is a black screen and no inputs working,
looks like the system just freeze. In /var/log/syslog I find no errors in the
suspend process, but there is absolutely no log entries what happens after I
wake up my laptop.
I then do a hard power off and the next log entry after suspend is just a new
boot process.
Maybe you have other suggestions, more options to play with, maybe some
specific logs I have to check? I'm still not giving up on this!
I don't understand how only radeon driver can cause such problems. I did not
did any more tweaks on this OS. Is this KMS/UMS related? It should be some
solution, I believe it!
Thanks