Re: [PATCH] mtd: nand: mxc: Fix mxc_v1 ooblayout

[Marek Vasut <marek.vasut@gmail.com>]

On 11/25/2016 10:13 AM, Boris Brezillon wrote:
> Commit a894cf6c5a82 ("mtd: nand: mxc: switch to mtd_ooblayout_ops")
> introduced a bug in the OOB layout description. Even if the driver claims
> that 3 ECC bytes are reserved to protect 512 bytes of data, it's actually
> 5 ECC bytes to protect 512+6 bytes of data (some OOB bytes are also
> protected using extra ECC bytes).
> 
> Fix the mxc_v1_ooblayout_{free,ecc}() functions to reflect this behavior.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Fixes: a894cf6c5a82 ("mtd: nand: mxc: switch to mtd_ooblayout_ops")
> Cc: <stable@vger.kernel.org>
> ---
>  drivers/mtd/nand/mxc_nand.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> index 61ca020c5272..c19ec4f0983e 100644
> --- a/drivers/mtd/nand/mxc_nand.c
> +++ b/drivers/mtd/nand/mxc_nand.c
> @@ -886,7 +886,7 @@ static int mxc_v1_ooblayout_ecc(struct mtd_info *mtd, int section,
>  		return -ERANGE;
>  
>  	oobregion->offset = (section * 16) + 6;
> -	oobregion->length = nand_chip->ecc.bytes;
> +	oobregion->length = 5;

Use a macro instead of hard-coding a value please :)

>  	return 0;
>  }
> @@ -908,8 +908,7 @@ static int mxc_v1_ooblayout_free(struct mtd_info *mtd, int section,
>  			oobregion->length = 4;
>  		}
>  	} else {
> -		oobregion->offset = ((section - 1) * 16) +
> -				    nand_chip->ecc.bytes + 6;
> +		oobregion->offset = ((section - 1) * 16) + 5 + 6;

DTTO here, the math here is cryptic enough.

>  		if (section < nand_chip->ecc.steps)
>  			oobregion->length = (section * 16) + 6 -
>  					    oobregion->offset;
> 


-- 
Best regards,
Marek Vasut