Possible problems if implementing system off by using pm_state_force with PM_STATE_SOFT_OFF

[piazzalo]

Hi kindly experts, I am studying Zephyr's system power management and discovering that some boards use PM_STATE_SOFT_OFF to implement their system off state.

Now, my device has a hard power-off requirement when it receives a shutdown reqeust.

However, I think there are few chances to fail to reach PM_STATE_SOFT_OFF during the system power management procedure.

1. Busy threads make IDLE thread to starve
2. In pm_system_suspend(), if pm_suspend_devices() returns non-zero, it will go to resume path and finally break the system off flow

Any suggestions or corrections are appreciated, many thanks.