Refer to section 8.2 of this document: i.MX53_START_Linux_BSP_UserGuide.pdf
In that section there is a recommended setting for the variable: bootargs_mmc.
Adding: ip=dhcp
will get u-boot to initialize eth0 and get an IP address.
If I did not have that parameter set, I found that I had to manually perform an ifconfig in order to bring up eth0 and assign an ip address (all after the system had come up and I logged in)
The other thing to note is that I'm running on a pretty minimal build. Not quite the bare minimum, but almost. See my earlier post:
http://imxcommunity.org/group/imx53quickstartboard/forum/topics/user-experience-with-1109-binaries-w...
Here's my setting so you can use copy/paste:
setenv bootargs_mmc 'setenv bootargs ${bootargs} root=/dev/mmcblk0p1 ip=dhcp rootwait rw video=mxcdi1fb:GBR24,VGA-XGA di1_primary vga'
JR
