Re: [PATCH 1/3] mtd: nand: omap: Revert to using software ECC by default

[Grazvydas Ignotas <notasas@gmail.com>]

On Tue, Aug 5, 2014 at 1:11 PM, Roger Quadros <rogerq@ti.com> wrote:
> For v3.12 and prior, 1-bit Hamming code ECC via software was the
> default choice. Commit c66d039197e4 in v3.13 changed the behaviour
> to use 1-bit Hamming code via Hardware using a different ECC layout
> i.e. (ROM code layout) than what is used by software ECC.
>
> This ECC layout change causes NAND filesystems created in v3.12
> and prior to be unusable in v3.13 and later. So revert back to
> using software ECC by default if an ECC scheme is not explicitely
> specified.
>
> This defect can be observed on the following boards during legacy boot
>
> -omap3beagle
> -omap3touchbook
> -overo
> -am3517crane
> -devkit8000
> -ldp
> -3430sdp

omap3pandora is also using sw ecc, with ubifs. Some time ago I tried
booting mainline (I think it was 3.14) with rootfs on NAND, and while
it did boot and reached a shell, there were lots of ubifs errors, fs
got corrupted and I lost all my data. I used to be able to boot
mainline this way fine sometime ~3.8 release. It's interesting that
3.14 was able to read the data, even with wrong ecc setup.

Do you think it's safe again to boot ubifs created on 3.2 after
applying this series?

-- 
Gražvydas