Why does deep sleep power management not work for me?

[Josef Wolf]

  root at x13:/# cat /proc/cmdline
  BOOT_IMAGE=/vmlinuz-6.8.0-44-generic root=UUID=f9dc833d-fb25-4cd5-8c59-c1d7cc8536e1 ro net.ifnames=0 quiet loglevel=4 mem_sleep_default=deep

deep sleep should be default...

  root at x13:/# pm-suspend
  root at x13:/# journalctl |grep suspend|tail -2
  Sep 13 11:13:40 x13 kernel: PM: suspend entry (deep)
  Sep 13 11:13:40 x13 kernel: PM: suspend exit

suspend exits immediately??

  root at x13:/# cat /sys/power/mem_sleep
  s2idle

I'd expected "s2idle [deep]" or something...

  root at x13:/# LANG= echo deep >/sys/power/mem_sleep
  bash: echo: write error: Invalid argument

huh?

Any hints?

-- 
Josef Wolf
jw at raven.inka.de