[Q] Using Micron 4-bit on-die ECC with v2.6.36 kernel?
Brian Foster
brian.foster at maximintegrated.com
Wed Jul 3 04:49:17 EDT 2013
On Wednesday 19-June-2013 14:40:45 David Mosberger-Tang wrote:
> Attached is a patch relative to 2.6.27.y. We use it with a 16-bit
> wide Micron part needing 4-bit ECC. It works for us, YMMV. I'm
> pretty sure the raw access is broken badly but we are not using that
> so it's not a problem from us. The patch assumes that on-die ECC is
> enabled in the bootstrap loader.
David,
Thanks! I've been working on getting our kernel and Das U-Boot
up to a common baseline w.r.t. the NAND-handling (including a
on-die compatible BBT layout in the OOB and other details), so
I had not looked too closely at your Patch until now-ish....
In examining it, I may have spotted an oddity: When counting
bit-flips, you only count them in the main-data area and in
the ECC-area (in the OOB). What you do not count are any in
the on-die ECC-protected bits in the OOB (which, in fact,
happens to be all of .oobfree).
Whilst not necessarily wrong, it does mean you may under-count
the true number of ECC-detected bit-flips, under-reporting the
number of corrections, and hence (inadvertently?) fooling the
system into thinking the block is in better health than it
really is.
Or I may mis-understanding something here....
cheers!
-blf-
--
Brian Foster
Principal MTS, Software | La Ciotat, France
Maxim Integrated | http://www.maximintegrated.com/
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