When I had discovered that my NAND flash had all bad blocks, I found a patch to dump the NAND blocks (which I think you had said you did). What I found in my case was that on one board 8 data lines were disconnected and on another one of the 0 ohm resistors was faulty (so one bit was always read as 0).
Might you have a hardware problem with your NAND? Who is the manufacturer of the NAND chip, what is its part number, and does u-boot have that part and its ID listed as a supported device?
Darrik
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Now i got all NAND stuffs from u-boot-1.3.4, including common/cmd_nand.c and drivers/mtd/nand/*, but still the same problem.
Other components of u-boot can influence NAND behavior?
I saw some people with similar problem using "nand scrub", but im little bit afraid with this command...
Another thing i notice: when reseting the board without turning off power, NAND is not found.