Bit flip detection after boot

[Richard Weinberger]

On Wed, Apr 13, 2016 at 11:25 PM, Raphael Pereira <raphael at rmi.inf.br> wrote:
> Hi,
>
> I have a custom board with a GPMI interface (Freescale i.MX233) with
> kernel 4.1.18 using Micron MT29F4G08ABADAWP (nand: 512 MiB, SLC, erase
> size: 128 KiB, page size: 2048, OOB size: 64).
>
> When I boot, the flash gets recognized and works flawless. I can
> ubiformat, ubiattach, mount, copy a lot of files, umount, remount,
> check and test in whatever way I need. No problem arrises.
> The problem is that when I shut the system down (turn it off) and boot
> again, all used blocks are marked as badblocks.

Sounds like you have a massive bitflip problem.
This is where you should start investigating.
Are you facing so massive bitflips that the bad block marker is wrongly set?

> I have used another flash (Toshiba with w/ erase size: 256KiB) and it
> works perfectly, with no problem at all.
>
> Trying to find out what might be the problem, I found BBT DTS option,
> so I enabled it and, instead of marking all blocks as bad, I end up
> with UBI detecting bit-flips on all sectors, but correctable flips, so

You've disabled the bad block scan and tried to paper over the root cause. ;)

> I can use the flash normally (although it takes a lot of time to boot
> because of the many messages "ubi0: fixable bit-flip detected at PEB
> XXX".
>
> I have changed the chip a lot of times and have checked my hardware
> and I am quite sure it is not a hardware problem. I think that some
> structure detection of the flash is wrong in the kernel for this
> particular case (i.MX233 BCH + MT29F4G08ABADAWP).
>
> Can someone guide me in debugging this problem?

As I said, find out why you're facing so much bitflips.

-- 
Thanks,
//richard