Multiple writes to NAND OOB...
manningc2 at actrix.gen.nz
Thu Sep 21 23:18:46 EDT 2006
On Thursday 21 September 2006 04:30, Siddharth Choudhuri wrote:
> I have the following question regarding multiple writes to OOB data:
> Is it possible to write to the OOB data of the same page multiple times ?
Yes it is **possible**, but be be careful. If you do too many writes without
an erase you can cause corruptions due to "write disturb".
> If so, does it mean that the bytes being written are to different
> locations(offsets) of the OOB because a byte cannot be rewritten in NAND
> unless its block is erased ?
If you write to NAND, then what you get is the ANDing of the pattern you write
against what was already there.
If a byte had 0011-0101 and you program 1101-0011 nto it you'll end up with
Thus, if you want to program a new pattern into some bytes, you use 0xff for
any bytes you don't want to change.
You need to do an erase to change bits back to 1.
Note a subtle difference. Most NOR writes will fail if you write a pattern
that tries to set a bit from 0 to a 1. On NAND, the bit will not change, but
it is not an error to try to do this.
More information about the linux-mtd