Useful info : Power down modes - NovasomIndustries/Utils GitHub Wiki

Power Down Modes on i.MX6

First of all set the device that will wake up the system.
Not doing so, the system will be recovered only from an hw reset

Set the wake up source, in this case tty

• echo enabled > /sys/class/tty/ttymxc2/power/wakeup

Go to memory suspend

• echo mem > /sys/power/state

Go to standby suspend

• echo standby > /sys/power/state