[PATCH 1/2] mtd: nand: add erased-page bitflip correction

[Brian Norris]

On Thu, Mar 13, 2014 at 07:01:13AM +0000, Pekon Gupta wrote:
> >From: Brian Norris [mailto:computersforpeace at gmail.com]
> >Really? So if you read a blank (all 0xff) page that has no bitflips, you
> >see an ECC error? I'm sorry, but I didn't realize that's how your
> >hardware worked. 
> >
> > That's the worst hardware ECC design I've seen so far
> >:(
> >
> - GPMC and ELM hardware engines were design during OMAP3 and earlier
>   time-frames. When only 1-bit Hamming was enough, and there were
>   hardly any bit-flips seen on erased-pages :-).
> - And I don't think h/w IP designers have too much visibility on actual usage
>   and software framework of these engines. So this remained un-changed.
> However, I do have internally raised this issue of getting a feature added
> in hardware to check for all(0xff). But still we have to support legacy devices.

I would think even a hardware designer could figure out that flagging an
ECC error every time you read an all-0xff erased page would be a bad
idea. And that has nothing to do with bit error rates.

Brian