[Yaffs] failed erases causing block retirement

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Author: Ben Gamsa
Date:  
To: yaffs
Subject: [Yaffs] failed erases causing block retirement
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?

-- 
Ben Gamsa       
SOMA Networks   312 Adelaide St. W. Suite 600 Toronto, Ontario, M5V1R2