I'm having this problem on two second hand hp business machines with ... I think discrete graphics but now that I'm writing this I never bothered to check. I'm running Ubuntu on them and they basically run Minecraft and flightgear a few times a day. Not every time, but eventually when either machine attempts to enter suspend mode it will instead crash and stay like this until a manual hard reset. I suspect this is related to certain software running when suspend is initiated but I'm not sure.
I'm not using Ubuntu much myself these days and I've never used a Radeon GPU, any advice or ideas would be appreciated. If anyone wants to dig in I can get hardware info and logs, I'm feeling lazy at the moment.
Check and search for dmesg errors first. Check linux-hardware.org for scans of the same machine. Look for any that are using other kernels that may have had better success. Run your own scan and upload it too so others can see.
The whole debian/Ubuntu primary use is for LTS kernel stuff. So you might be on an older kernel. All GPU stuff is kinda edgy for what the preconfigured options are set to by default. All distros have a purpose and what they are good at. The best documentation for custom kernel configurations comes from Gentoo in my opinion.