Re: [Yaffs] failed erases causing block retirement

On Friday 29 May 2009 07:25:59 Ben Gamsa wrote:
> To partially answer my own e-mail, it looks like the problem is some
> missing locking in some local extensions to the mtd nand driver that is
> causing the erase command to sometimes fail.

Normally these types of problem are somewhere in the mtd layer.

>
> Ben Gamsa wrote:
> > I'm seeing quite a few failed erases on my system using a Micro
> > 29F4G08AAC flash part. This results in the bad block count growing
> > quite quickly. However a scrub and rescan shows only the original
> > blocks marked bad out of manufacturing are actually bad. Changing the
> > yaffs code to retry (just once) an erase that fails, always seems to
> > show the second erase succeeding (although I've only seen a handful of
> > erase failures since trying the change). I've seen some discussion that
> > perhaps the bad-block detection algorithm is overly aggressive at
> > marking blocks bad, so I'm wondering if it's safe to retry the erase and
> > consider everything good if the second erase succeeds?

It is safe to retry erases from a yaffs perspective, but if blocks are really
failing erases (ie. not just a driver issue) I would be a bit concerned as
to their health and would not want to reuse those blocks.

-- CHarles