[systemd-devel] systemd suspending docked laptop?

[Jan Bakuwel]

Hi all,

ii  systemd 237-3ubuntu10.3                     amd64        system and 
service manager
ii  systemd-sysv 237-3ubuntu10.3                     amd64        system 
and service manager - SysV links

running on a 64bit Linux Mint 19 (based on Ubuntu Bionic) Dell Latitude 
laptop.

Either NetworkManager or systemd is suspending the system after it is 
powered up when the laptop is docked with the lid closed. This does not 
happen when the laptop is used without the docking station (and lid open).

Oct 17 08:33:49 l1 systemd[1]: Started Disk Manager.
Oct 17 08:33:49 l1 systemd[1]: Reached target Graphical Interface.
Oct 17 08:33:49 l1 systemd[1]: Started Stop ureadahead data collection 
45s after completed startup.
Oct 17 08:33:49 l1 systemd[1]: Starting Update UTMP about System 
Runlevel Changes...
Oct 17 08:33:49 l1 NetworkManager[1312]: <info> [1539718429.0768] 
manager: sleep: sleep requested (sleeping: no enabled: yes)
Oct 17 08:33:49 l1 NetworkManager[1312]: <info> [1539718429.0769] device 
(wlp3s0): state change: unavailable -> unmanaged (reason 'sleeping', 
sys-iface-state: 'managed')
Oct 17 08:33:49 l1 NetworkManager[1312]: <info> [1539718429.0774] 
manager: NetworkManager state is now ASLEEP
Oct 17 08:33:49 l1 systemd[1]: Reached target Sleep.
Oct 17 08:33:49 l1 systemd[1]: Starting Suspend...
Oct 17 08:33:49 l1 systemd[1]: Started Update UTMP about System Runlevel 
Changes.
Oct 17 08:33:49 l1 systemd-sleep[2197]: Suspending system...
Oct 17 08:33:49 l1 kernel: [   30.151723] PM: suspend entry (deep)

This also did not happen with the previous version of Linux Mint 18 
(based on Ubuntu Xenial).

ii  systemd 229-4ubuntu21.2                              amd64        
system and service manager
ii  systemd-shim 9-1bzr4ubuntu1                               
amd64        shim for systemd
ii  systemd-sysv 229-4ubuntu21.2                              
amd64        system and service manager - SysV links


I suspect systemd is initiating the suspend but it's not clear from the 
logs. Is there a way to increase systemd's verbosity? Any suggestions 
how to fix this small but rather (daily) annoying problem? The system 
should obviously not suspend itself when it's used with a docking 
station and external monitors. The lid needs to stay closed so the 
system uses the external monitors and not the laptop screen.

regards,
Jan