Problem of coldboot on i.MX27 board with Micron NAND

Hello,
I have a problem with redboot (release 20050912) with Freescale patches 
for i.MX27 PDK (3-stack) and seems to be related to NAND chip (all other 
components are identical).
When I power on the board, nothing happened on serial console but when I 
press reset button (or if I reset board using JTAG, to board boot properly.

With NAND Numonyx NAND02G-B2D, it works well on power on but with Micron 
MT29F2G08ABBEAH4, coldboot does not work, I have to press RESET button.

The specs seem to be similar. The only difference is a device 
initialization for Micron that says that host must wait 100us after VCC 
is applied before sending Reset (FFh) command.
Where have I to place the wait loop ?
At the beginning of In PLATFORM_SETUP1 macro (.macro _platform_setup1) 
in hal_platform_setup.h or anywhere else ?

Test is done on boards with i.MX27 CPUs that have different revision 
(200951, 201209). And I know that newer revison (starting from 2012) can 
freeze at boot due to bug in PLL circuit.
Do you have any other leads for me ?

Thank you for your help.

Gaëtan Carlier.

ps : Of course, I have tried MT29 NAND on several board (that works with 
NAND02G chip) but same result.

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