OMAP-L138: Can I use McASP AFIFO in any size?

Part Number:OMAP-L138

Hi Champs,

The McASP AFIFO size is 256-byte each for read and write. In the case of two data pins, it's 32 32-bit words per serializer.
So, my question is the size is fixed or not. Can I change the size? For example, I'd like to set it to 16 32-bit words per serializer in the case of 2 data pins due to minimizing latency. 

Regards,
j-breeze