Created attachment 117828 [details]
dmesg output

Hibernation works perfectly when using the integrated Intel GPU, but
it only works once when using the discrete AMD Radeon R7 265.

I am testing different GPUs by changing the primary GPU in BIOS.

When trying to hibernate for the second time, I see one of 2 outcomes:
1. Display powers off, but the system stays on and stops responding to
   ICMP pings and sysrq; after reset the system boots afresh and fsck
   is run.
2. System powers off, but doesn't resume on next boot: boots afresh and
   fsck is run.

More observations:
* Suspend to RAM works every time.
* Hibernation works every time as long as X has not been started.
* I am running Arch Linux, swap is on an SSD and not encrypted. I usually start
hibernation with `systemctl hibernate`, but writing to /sys/power/state has the
same effect.

I have no idea how to debug this issue, but would be happy to do it with your
help.