/dev/mtdblock acts wrong....

[Kim, Sanghun]

when I command "    dd of=/dev/mtdblock0 if=jffs.img"

my linux reports...
===================================
mtdblock_open
ok
ll_rw_block: Trying to read nonexistent block-device 1f:00 (0)
/dev/mtdblock_release
mtdblock0: Input/output error
nand_sync:called
ok
====================================

We have verified functions of nand flash driver(spia.c)
And works well. (read, write, out-of-band read/write)
Still, Ecc does not verify(Errors occured if ECC flag on)

If I want to use JFFS.. Do I need "ECC Flag Activate"?

..........................

and JFFS reports 
 *JFFS: Trying to mount device 1f:00.
 *jffs_scan_flash(): start pos = 0x0, end = 0x8388608
 *jffs_scan_flash(): Bad checksum: checksum = 6926185, raw_inode.dchksum =
 3009104
 *jffs_scan_flash(): Bad checksum: checksum = 3552929, raw_inode.dchksum =
 1302987
 *jffs_scan_flash(): 0xff at pos 0x49960.
 *jffs_scan_flash(): 0xff ended at pos 0x65536.
 **************** Dirty flash memory or bad inode: hexdump(pos = 0x65536,


How to solve it? 

Please advice ~~