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power up sequence in Blackfin

In my BF533 board, I used 2 seperate power supplier chips, one for 3.3V and one for 1.2V.
1.2V is available for Vint, about 3ms before 3.3V is available for Vext. Then Reset signal is provided to boot BF533, but I always found that BF533 could not give out CS signal, and could not boot from external Flash then,unless I reprovide the Reset signal(That is , at least 2 Resets are needed).
I've tried to provide 3.3V at first, then 1.2V. BF533 could boot correctly after provide one reset signal, no need to reprovide the reset signal.
I've checked all signals: RESET, NMI, BMODE0-1 using osciloscope, and there's no abvious noise, and all signals seem correct.
I saw someone has also asked similar questions on BF52X,the answers are all that there's no limitation about power provider sequence. Have someone ever provided Vint before Vext and booted successfully?