[U-Boot-Users] u-boot on nadflash for at91sam9260ek

[Stefan Roese <sr@denx.de>]

Hi Victor,

On Thursday 07 June 2007, Victor Librado wrote:
> 2)In u-boot. I redefined the block of the nandflash for environment
> variables :
>
> #ifdef CFG_ENV_IS_IN_NAND
> #define CFG_ENV_OFFSET  0x80000         /* environment starts here  */
> #define CFG_ENV_SIZE    0x20000         /* 1 sector = 128kB */
>  #endif
>
>
> Now saveenv works properly! I think it was previously a bad block in my
> nandflash?

That can always happen. And the code *should* be able to handle this. If it is 
not able to handle this situation right now (sorry, I don't know for sure), 
then we (you? ;-)) should fix this. Patches always welcome.

> I have a doubt, if I define the soft ECC (both linux, u-boot), the OOB
> section of each page of the SAMSUNG nandflash the board has (64 bytes),
> how will it be filled? Because the nandflash datasheet states that in a
> block the first byte of the OOB section in the 1st o 2nd pages must be
> FFh or it is a bad block. So it could be that ECC data (the 4 byte hw or
> software ECC) were written in this first byte of the OOB and mark the
> block as invalid for this nandflash....... (so every write will generate
> a bad bloack?)
>
> In u-boot the eccmode:
>
> nand->eccmode = NAND_ECC_HW12_2048; /* NAND_ECC_SOFT;*/
>
> What part of the OOB writes?

See drivers/nand/nand_base.c

static struct nand_oobinfo nand_oob_64 = {
	.useecc = MTD_NANDECC_AUTOPLACE,
	.eccbytes = 24,
	.eccpos = {
		40, 41, 42, 43, 44, 45, 46, 47,
		48, 49, 50, 51, 52, 53, 54, 55,
		56, 57, 58, 59, 60, 61, 62, 63},
	.oobfree = { {2, 38} }
};

So the ECC positions are: 40, 41, 42 etc, as defined above.

> I'm getting really confused... any help will be welcomed.
>
> Can ECC disabled in nandflash u-boot with some compilation option?

Not an compilation option, but a NAND driver option:

	this->eccmode = NAND_ECC_NONE;

instead of 

	this->eccmode = NAND_ECC_SOFT;

But I wouldn't recommend this. Using NAND without ECC is definitely not a good 
idea. Even for reading. So we should try to investigate further and fix the 
source of the problem. Please stick with NAND_ECC_SOFT for now, since it is 
known to work on other platform, and we have less possible error sources 
(like CPU specific HW-ECC code).

Hope this helps a little.

Best regards,
Stefan

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