Re: [YAFFS] bad block management policy

Artem Bityutskiy
2012-08-24T11:39:50Z

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On Thu, 2012-08-09 at 10:24 -0400, Peter Barada wrote:
> You could modify YAFFS to ignore -EUCLEAN returns from MTD which will
> prevent YAFFS from marking blocks bad prematurely, but then there is no
> way to predict when a block is about to wear out and return
> uncorrectable errors (-EBADMSG).

We recently improved this area and now you also can set the bitflip
threshold in the MTD so that MTD won't return -EUCLEAN unless the amount
of bits flipped is larger than the threshold. The idea is that UBI
scrubs eraseblocks (moves data to different ones) in case of bitflips.
But 1-bit flips happen so often on some devices, that it is wiser to
ignore those. So now the driver can set the level on which MTD will
start returning -EUCLEAN. Below that flip level, it will return 0.

So this also means that if you set the threshold = ECC strength, you
should never even get -EUCLEAN. Not sure it is good idea, but a
possibility as well.

--
Best Regards,
Artem Bityutskiy

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