Re: Increased frequency of fastmap failure due to CRC mismatch

[Richard Weinberger <richard@sigma-star.at>]

Ronak,

Am Freitag, 18. Mai 2018, 15:50:47 CEST schrieb Ronak Desai:
> Hey Richard,
> 
> On Thu, May 17, 2018 at 11:49 AM, Richard Weinberger
> <richard.weinberger@gmail.com> wrote:
> > On Thu, May 17, 2018 at 5:47 PM, Ronak Desai
> > <ronak.desai@rockwellcollins.com> wrote:
> >> We are at kernel 4.1.8.
> >
> > Woah, this kernel is very old, did you backport _all_ ubi/fastmap fixes?
> 
> No, I did not backport all the changes in ubi/fastmap as considering
> the product state it is not feasible. This product has been tested for
> several months and I checked all the paths in NAND-MTD subsystem as
> well as in NAND controller specific driver but nothing stood out which
> can cause this. I also compared the basic routines with latest kernel
> and I don't see any major changes or fixes which I can relate to this
> failure.

Well, I can guarantee you that fastmap is broken in 4.1.

> The only thing that bothers me is that NAND-MTD system return without
> any error except it reports that it has corrected greater or equals to
> bits on that block but still UBI finds corrupted fastmap. So, either
> there is something wrong in the ECC algorithm where it thinks it has
> corrected the bits but actually it did not or something is wrong in
> UBI fastmap. Also, as I mentioned on every power-up we see this
> fixable bit flip message on that specific block but fastmap fails only
> few times and not always.

Do mtd/ubi tests pass?

Thanks,
//richard

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