RE: [EXT] [PATCH v2 3/3] mtd: rawnand: micron: Address the shallow erase issue

["Bean Huo (beanhuo)" <beanhuo@xxxxxxxxxx>]

Hi, Boris, Richard 

> >
> > A missing VID header plus good payload will cause UBI to stop
> > attaching since it violates the IO model.
> 
> Sure, and that's not what we want to do anyway. We basically have 2 choices
> here:
> 
> 1/ overwrite all pages starting from page 0 and ending at page 15. This will lead
> to ECC errors on already written pages, and 0-filled pages for others (unless we
> go for a raw write, in which case it might actually lead to ECC errors depending
> on the engine).

No need for overwriting all pages. I overwrite EC and VID page just for prevent of 
Erase power loss issue. But you hate this since FS-specific approach.
According to Richard's emails, we don't need to overwrite page0,  overwrite page1
Is enough.

> 2/ track already written pages (by reading them first), and only writes those that
> have not been written yet. That means no ECC error in that case, and no
> corrupted EC/VID header as well.

This is similar with my patch approach, but corrupted EC and VID headers. 

I have two proposals:
1.  rebase my patch, and copy one idea from Miquel's patch which records the programmed pages.
But page 1 should be overwrote considering the UBIFS re-erase mechanism.

2.  add a new padding structure in the MTD,  which is used to filling empty page in the MTD.
And once FS layer detects this padding data, just ignore or trigger re-erase this block. 

How about you?

Thanks,

Bean

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