Re: Raw NAND bad block marker positions

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

Hi Frieder,

Schrempf Frieder <frieder.schrempf@xxxxxxxxxx> wrote on Wed, 12 Dec
2018 10:32:04 +0000:

> Hi,
> 
> the current implementation for checking/setting the bad block markers in 
> raw NAND flash devices supports three setups for the position of the 
> markers within the bad block:
> 
> * BBM in first page only
> * BBM in last page only
> * BBM in first or second page
> 
> This is controlled by the flags NAND_BBT_SCANLASTPAGE and 
> NAND_BBT_SCAN2NDPAGE. It is not supported to set both flags to check 
> first, second and last page.
> 
> Though some devices seem to require this kind of setup. We know of some 
> ESMT SLC NANDs, that were accidentally shipped with BBM in the first or 
> last page, instead of first or second page as claimed in the datasheet.
> 
> Also the documents for Cypress/Spansion/AMD NANDs claim that the 
> software needs to check first, second and last page for BBMs (e.g. [1]).
> 
> It doesn't look like it would be difficult to make NAND_BBT_SCANLASTPAGE 
> and NAND_BBT_SCAN2NDPAGE work together, but I wanted to ask if someone 
> already stumbled upon this problem or if someone has any comments or 
> suggestions, before trying to patch this?

I don't, but I would welcome such change, I don't think it is very
invasive anyway.


Thanks,
Miquèl

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