I have tested this on a NanoPi R5C as well as on NanoPC-T6 (non-LTS). For the later I also tested a vender provided Kernel / OS Installation.
What happens is that whenever some Power-Saving is requested, the board will seemingly fully power down and is not responsive to anything,
at best the reset button will do its work, R5C requires a power-cycle.
The last kernel msgs are these (see https://www.kernel.org/doc/Documentation/power/states.txt😞
# echo freeze > /sys/power/state
[ 54.373374] PM: suspend entry (s2idle)
[ 54.671033] Filesystems sync: 0.297 seconds
[ 54.775176] Freezing user space processes
[ 54.780065] Freezing user space processes completed (elapsed 0.004 seconds)
[ 54.780769] OOM killer disabled.
[ 54.781078] Freezing remaining freezable tasks
[ 54.782928] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[ 54.791332] r8169 0002:01:00.0 wan1: Link is Down
I am at a loss how to diagnose this further. To me it appears that there is some vital power-source to CPU or RAM switched off.
