[U-Boot] Layout of OOB data in NAND flash

[Gaer, A.]

Hi!

It seems like the layout of OOB/4-Bit-ECC data in NAND flash differs from RBL/UBL to u-boot/linux (at least on a DM365 device). Is there any good reason for this?

As far as I understand, the RBL/UBL uses this layout (2048 byte pages):

(E = ECC byte, X = other oob)

XXXXXXEE
EEEEEEEE
XXXXXXEE
EEEEEEEE
XXXXXXEE
EEEEEEEE
XXXXXXEE
EEEEEEEE

The u-boot/linux drivers seems to use this instead:

XXXXXXXX
XXXXXXXX
XXXXXXXX
EEEEEEEE
EEEEEEEE
EEEEEEEE
EEEEEEEE
EEEEEEEE
 
The ECC bytes seem to be packed in the same way, though.

The different layout means that it is impossible to update UBL/u-boot from u-boot or linux.

I would really like to add a config option to u-boot/linux that enables the RBL/UBL layout also in u-boot/linux. Any objections to this?

Another question: 512 byte pages in linux seem to have a really funny oob layout

EEEEEXEE
XXXXXEEE

Does anybody know the reason for that? (I know the 6th byte is the manufacturer bad-block marker. But why not just put the ECC data into the last 10 byte of oob like RBL/UBL do it?)

Regards,
 Andreas.

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Andreas Gäer, Senior Software Engineer

Basler Vision Technologies
An der Strusbek 60-62
22926 Ahrensburg
Germany

Tel. +49 (0) 4102 - 463 517
Fax +49 (0) 4102 - 463 46 517 

mailto:Andreas.Gaer at baslerweb.com
http://www.baslerweb.com

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