[PATCH] MTD: fix s3c2410 error correction

[Matt Reimer]

Anybody willing to ACK this patch? It definitely fixes the problem I'm
seeing on a s3c2440a. For more information, compare the s3c2440a or
s3c2410 manuals with page 8 of the following documentation:

http://www.samsung.com/global/business/semiconductor/products/flash/downloads/applicationnote/ecc_algorithm_for_web_512b.pdf

Matt


On 10/18/07, Matt Reimer <mattjreimer at gmail.com> wrote:
> From: Matt Reimer <mreimer at vpop.net>
>
> The single-bit error correction was, well, incorrect. For determing which
> bit to correct it was using P1' P2' P4' P8' instead of P1 P2 P4 P8, and
> it was using P16' P32' P64' P128' P256' P512' P1024' P2048' instead of
> P16 P32 P64 P128 P256 P512 P1024 P2048.
>
> Signed-off-by: Matt Reimer <mreimer at vpop.net>
> ---
>  drivers/mtd/nand/s3c2410.c |   26 ++++++++++++--------------
>  1 files changed, 12 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/mtd/nand/s3c2410.c b/drivers/mtd/nand/s3c2410.c
> index 903db18..077fdcc 100644
> --- a/drivers/mtd/nand/s3c2410.c
> +++ b/drivers/mtd/nand/s3c2410.c
> @@ -364,23 +364,21 @@ static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat,
>             ((diff2 ^ (diff2 >> 1)) & 0x55) == 0x55) {
>                 /* calculate the bit position of the error */
>
> -               bit  = (diff2 >> 2) & 1;
> -               bit |= (diff2 >> 3) & 2;
> -               bit |= (diff2 >> 4) & 4;
> +               bit  = ((diff2 >> 3) & 1) |
> +                      ((diff2 >> 4) & 2) |
> +                      ((diff2 >> 5) & 4);
>
>                 /* calculate the byte position of the error */
>
> -               byte  = (diff1 << 1) & 0x80;
> -               byte |= (diff1 << 2) & 0x40;
> -               byte |= (diff1 << 3) & 0x20;
> -               byte |= (diff1 << 4) & 0x10;
> -
> -               byte |= (diff0 >> 3) & 0x08;
> -               byte |= (diff0 >> 2) & 0x04;
> -               byte |= (diff0 >> 1) & 0x02;
> -               byte |= (diff0 >> 0) & 0x01;
> -
> -               byte |= (diff2 << 8) & 0x100;
> +               byte = ((diff2 << 7) & 0x100) |
> +                      ((diff1 << 0) & 0x80)  |
> +                      ((diff1 << 1) & 0x40)  |
> +                      ((diff1 << 2) & 0x20)  |
> +                      ((diff1 << 3) & 0x10)  |
> +                      ((diff0 >> 4) & 0x08)  |
> +                      ((diff0 >> 3) & 0x04)  |
> +                      ((diff0 >> 2) & 0x02)  |
> +                      ((diff0 >> 1) & 0x01);
>
>                 dev_dbg(info->device, "correcting error bit %d, byte %d\n",
>                         bit, byte);
> --
> 1.5.3.2
>
>
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