In my opinion,it is not easy to modify u-boot.
I do the following things to fix this problem.
First:use QCVS to generate the memory initialization script.
Second:use Code Warrior to generate some T2080 RAM debug project
Third:copy the memory initialization script to T2080 RAM debug project initialization script,may need some modification
Debug custom board until memory can be accessed correctly.
Then I get the right configuration.
Next find some discrete memory initialization examples from u-boot code(like p1020,etc)
and modify T2080 u-boot memory initialization code.