DRV8801A-Q1: mode, no decay

Part Number:DRV8801A-Q1

Hi~

Customer want to use DRV8801A-Q1 but they can use least pin count.

So, by using just  Phase(#1) and Enable(#4), they want to control direction and speed.

I doubt when EN=0, have to use decay mode? even fast or slow?

When not use Mode 0, Mode 1, how to pin connection? NC or connect to ground?

Let me have your advice.

Thanks.