I have upgraded my LibreELEC system to an AMD one (CPU/motherboard/video card). After the upgrade LibreELEC was consistently freezing on resuming from sleep state S3. However, this did not happen when I booted other Linux distros in the same system. After spending a lot of time troubleshooting this issue (including playing with firmware settings and kernel parameters) I finally found out the culprit:
LibreELEC kernel is built with this patch that disables async suspend/resume by default. This can be verified at runtime via /sys/power/pm_async.
It is possible to re-enable it:
After this change, my system consistently resumes from suspend. I have not experienced a single freeze with it enabled.
To make this change persistent, I created this file:
Posting here hoping that this recipe will prove useful to others here.