DRV8214: Position Resolution from Ripple Counting

Hi, I am looking into solutions that allow me to control the speed and know the position of a very small motor and came upon the DRV8214. This part looks to have most of the features I want, however I can't find much information on the position measurement, in particular I want to know what determines the position resolution. 

Is the position measurement only dependent on the number of commutator poles, if so, is the resolution of the position equal to the physical spacing between commutator poles, or are there other factors that are used to get a more accurate position?

Thanks!