How to enable cache in U-boot

Hi, All

There are always a warning message on u-boot start:

U-Boot 2013.10 (Jan 06 2014 - 14:10:46)

I2C: ready
DRAM: 256 MiB
WARNING: Caches not enabled
NAND: 256 MiB

I just implement splash bmp display which is slow, so that I believe the cache is NOT enabled really. Thanks for any suggestion to fix the issue. 

Another issue of speed is nand read which take quite a few seconds to load zImage into DDR3. Are there any patch available to speed up nand reading in em335x_evm? Thanks.

BR

Cheng Shi

emtronix