booting arm board

I am trying to boot a foxg20 board. It uses an at91sam9g20 chip an used to work in linux 3.5. I am looking for some advice on how to get mainline linux to boot on it. I first tried bisecting and found this commit: 4cf3326ab5f34a333a46c59d0d3783db9cef13bf which is where it wouldn't boot I figured I should understand what broke, I ended up simply upping MMC_CMD_RETRIES from 3 to 10. So I was able to boot the version that caused it to not work. This change doesn't fix the lastest has unified some of the driver code. My question is: What is a good way to boot the latest kernel? Should I see where it breaks then keeping fixing that and moving forward or should I just start with the latest and take it from there?