How to test ecc correction code?

[Shannon Holland]

Hello,

We're developing for a Samsung S3C2410 based system  (currently running 
linux 2.6.10-rc3-bk2) and are using the internal hardware error 
correction code from the cpu's nand controller (3 byte ecc for a 512 
byte page). I "think" I've written some code to correct errors but am a 
tad stumped as to how to test it.

I had initially tried to read a block of data (including oob) using 
nanddump, then erase the block, change a single bit in the first page 
of my dumped data and re-write it to flash using nandwrite (specifying 
-o as I include oob data). However, the first call to write the OOB 
data in page 0 will fail.

At the shell level I'm doing:

# get the block of data with oob
nanddump -a 0 -l 16384 /dev/mtd3 > /tmp/nand

# some magic to flip a bit in the first byte of /tmp namd

# erase the block
flash_erase /dev/mtd3 0 1

#re-write with bad bit
nandwrite -s 0 -o /dev/mtd3 /tmp/nand

The call to nandwrite when it attempts to write the oob data for the 
first page (the ioctl(fd, MEMWRITEOOB) it returns an I/O Error.

Am I doing this correctly? Is there a better way to do this? Do any 
tools for this exist?

Thanks for any help!

Shannon