The mmc switch was misbehaving for me. This fixes the problem:
https://github.com/mvduin/u-boot/commit/fa320a46aa4ca37803d3b2262f4d60d344323587

The rest of the master branch of that repository is some experimentation I did to see if I could get some of the features of the dra7 and beaglebone u-boot's working, and to get a bit more familiar with the u-boot source code.

Highlights:
I've also explored how ram init is done, but haven't yet attempted to get it to recognize the 4 GB.

I'm afraid that most of the work and play is in one big commit. I should probably try to separate out the more useful stuff, but that's not going to happen today anymore :-)

Matthijs