Memory Address & BA pin routing

What’s the reason for for mixing DDR3L BA pins to address bus instead of using dedicated DDR_BA pins? For example DDR_A15 pin goes to BA1 pin of memory IC. Is it only to help layout routing? Can we route the BA pins directly to corresponding BA pins of memory IC and same with address pins? Effect to SW?

Yes, it is for route easily, The BCT file need change to reflect the swapping.
The interface design guide have the description and some placement and swapping option