Power saving mode - Lichee Pi Zero

Hi, Just got my Lichee Pi zero board.
I want to put it in deep sleep mode and wake it up with an external trigger.
I couldn’t find a way to do so. Is it even possible with this SoC?
Thanks.

Hi, it is really hard to do sleep mode for sdram based linux board if sdk not support…
In this time you can only shutdown to save power.