Right, I got it backwards, and people were polite and helpful in correcting me. For the uninitiated, it’s not obvious how to interpret that string. Here’s how I understand it now:
example of deep sleep disabled:
[jeremy@fwfedora ~]$ cat /sys/power/mem_sleep
[s2idle] deep
[jeremy@fwfedora ~]$
example of deep sleep enabled:
[root@fwfedora ~]# cat /sys/power/mem_sleep
s2idle [deep]
[root@fwfedora ~]# ```