Lenovo launched there Vibe P1smartphone back in 2015 with Android Lollipop as the base operating system.
Now the company has started rolling out the Marshmallow update for it. The news has been confirmed it in there forum. The post in forum says, “We expect Marshmallow to be rolling out for the Vibe P1, P1A42, over the next few days” Since the company has started rolling out Marshmallow update through OTA, it may take few time to reach to your device as update is available in stages. Marshmallow update brings some goodness like Doze mode, app standby, apl permission etc.