problems mounting >3.3MB JFFS2 partitions on Dataflash on AT91RM9200DK

[Aras Vaichas <arasv@magellan-technology.com>]

I can't seem to mount a partition greater than about 3.3MB. All 
partitions below this size *seem* to work fine.

a partition of this size will mount:
hex: 0x34c980, decimal: 3459456, erase blocks: 3276

a partition greater than or equal to this size will NOT mount:
hex: 0x34cda0, decimal: 3460512, erase blocks: 3277

I am running Linux-2.4.6-VRS-1 on the AT91RM9200DK development board. I 
have tried using command line partitions and setting at91_dataflash.c, 
it makes no difference.

My kernel command line is:

root=/dev/ram=rx initrd=0x21100000,6000000 ramdisk_size=15360 
console=ttyS0,115200,mem=32M
mtdparts=dataflash0:1047552(kernel_image)ro,0x400080(4MB_part),0x3000
60(3MB_part),-(the_rest)

This gives:
dev:    size   erasesize  name
mtd0: 00200000 00010000 "Physically mapped flash"
mtd1: 000ffc00 00000420 "kernel_image"
mtd2: 00400080 00000420 "4MB_part"
mtd3: 00300060 00000420 "3MB_part"
mtd4: 00040320 00000420 "the_rest"

mtd3 and mtd4 will mount, mtd2 will not mount. e.g.

$mount -t jffs2 /dev/mtdblock/2 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/mtdblock/2,
        or too many mounted file systems
[root@AT91RM9200DK /root]$

I did notice one other strange thing. I turned on a DEBUG option in 
at91_dataflash.c that showed all access to the dataflash device. When I 
mounted the mtd3 or mtd4, it showed reading activity going on with the 
dataflash. But when I mounted mtd2, the dataflash was not even accessed. 
It is like the software isn't even getting that far.

e.g. mounting mtd4, note the debug output

[root@AT91RM9200DK /root]$mount -t jffs2 /dev/mtdblock/4 /mnt/4
dataflash_read: 8387808 .. 8388864, 1056, 0x0420 bytes
READ: (e8) f8 38 0
   data: 85, 19, 03, 20, 0c, 00, 00, 00, b1, b0, 1e, e4, ff, ff, ff, ff,
dataflash_read: 8387808 .. 8387820, 12, 0x000c bytes

... SNIP ...

dataflash_read: 8648720 .. 8648764, 44, 0x002c bytes
READ: (e8) ff f0 50
   data: 85, 19, 01, e0, 2c, 00, 00, 00, 5f, 56, f1, e0, 01, 00, 00, 00,

[root@AT91RM9200DK /root]$mount
/dev/rd/0 on / type ext2 (ro)
/proc on /proc type proc (rw)
/dev/mtdblock/4 on /mnt/4 type jffs2 (rw)


e.g. mounting mtd2, note the lack of debug output

[root@AT91RM9200DK /root]$mount -t jffs2 /dev/mtdblock/2 /mnt/2
mount: wrong fs type, bad option, bad superblock on /dev/mtdblock/2,
        or too many mounted file systems

It doesn't even access the dataflash. So I suspect that something in a 
higher layer is saying that this partition isn't valid.

Any help or hints would be appreciated.

Aras