Mint 17.2 Wakes Up a Few Seconds After Suspending

Symptom:

After selecting “Suspend” from the session dialog, the computer goes to sleep and wakes up on its own a few seconds later.

Cause:

Probably cause it network adapter hardware, driver or firmware.

Solution:

Uncertain.

Troubleshooting Steps:

1. Unplugged USB mouse, keyboard and network cable
2. Restarted PC
3. Checked system log -> does not indicate what woke the computer up (“ACPI: Low-level resume complete”)
4. Checked suspend log -> /var/log/pm-suspend.log
5. Disabled wake up capable devices
   1. List wake up capable devices -> acpitool -w
   2. Disable particular device -> acpitool -W [Device No.]
   3. In my case, disabled GLAN, EHC1, EHC2, & HXC
6. Removed e1000e module, shutdown VirtualBox virtual machines (Win 8.1 IE 11 Virtual Machine may be a cause), then re-added the module
   1. sudo rmmod e1000e
   2. double-check that GLAN is still disabled with acpitool -w
   3. Computer will now sleep without waking up.
   4. sudo modprobe e1000e
7. Re-enable wake up devices with acpitool -W [Device No.]
8. Restarted computer. Launched various apps (Chrome, Firefox, Virtual Box + VMs) and tried to suspend PC. Works for now.