Micron MT28F128J3 RP JFFS2 error

[z l]

We have a ARM (Cirrus EP9315) based SBC with 2 FLASH
chips, we used both Micron and Intel chips, 32MB
total.  The JFFS2 driver will give,

jffs2_scan_eraseblock(): Magic bitmask 0xXXXX not
found at 0xXXXXXXXX 

errors when the MTD was re-mounted after umount.  But
only on the boards with Micron chip not on the Intel. 
Googling the net I realized that there are slight
difference between the 2 chips.  Can someone kindly
point me to where I should start to look in order to
solve this problem?

The Linux kernel is 2.4.21.