Why not check Linaro u-boot/kernel for this board? I am using 3.1 kernel
and 2012.02 u-boot - both from Ubuntu 'precise' repository.
I'm fairly new to the iMX53 and I'm just getting started so I don't know
much about Linaro's kernel/uboot for this board. I basically stared
with the Freescale BSP for the iMX53 QSB as they make the board and have
scavenged additional information from various places around the web.
I've now got a working u-boot and kernel that I'm generally happy with
except for sata issues I'm currently dealing with. I'll check out
Linaro's information if I continue to have problems.