Power saving and changing clock speed on SAM9-L9260

I’m trying to save power on an Olimex SAM9-L9260 board. However I am having problems when I reduce the master clock speed to 45MHz - I have trouble accessing the NAND flash. I’ve tried re-programming the SMC3 settings for accessing the NAND but I still have problems.

I basically halved all the clock speeds in the system - so the processor clock runs at 90.112MHz and the master clock runs at 45.056MHz. Everything seems to be going ok until I try accessing the NAND during u-boot boot up.

System:

at91bootstrap 2.3

u-boot 1.2.0

linux 2.6.30