[PATCH v2 3/3] Add 4-bit ECC support for large page NAND chips on Davinci
Troy Kisky
troy.kisky at boundarydevices.com
Thu Jun 18 17:16:22 EDT 2009
s-paulraj at ti.com wrote:
> From: Sandeep Paulraj <s-paulraj at ti.com>
>
> The patch applies to linux-mtd GIT tree
>
> This patch adds 4-bit ECC support for large page NAND chips using the new ECC
> mode NAND_ECC_HW_OOB_FIRST. The platform data from board-dm355-evm has been
> adjusted to use this mode.
>
> The patches have been verified on DM355 device with 2K and 4K page size
> Micron devices using mtd-tests.
> Error correction upto 4-bits has also been verified using
> nandwrite/nanddump utilities.
>
> Reviewed-by: David Brownell <dbrownell at users.sourceforge.net>
> Signed-off-by: Sandeep Paulraj <s-paulraj at ti.com>
> Signed-off-by: Sneha Narnakaje <nsnehaprabha at ti.com>
> ---
> drivers/mtd/nand/davinci_nand.c | 65 ++++++++++++++++++++++++++++++++++----
> 1 files changed, 58 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index ba6940d..2ff0712 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -500,6 +500,49 @@ static struct nand_ecclayout hwecc4_small __initconst = {
> },
> };
>
> +/* An ECC layout for using 4-bit ECC with large-page (2048bytes) flash,
> + * storing ten ECC bytes plus the manufacturer's bad block marker byte,
> + * and not overlapping the default BBT markers.
> + */
> +static struct nand_ecclayout hwecc4_2048 __initconst = {
> + .eccbytes = 40,
> + .eccpos = { /* 2 bytes at offset 0 hold the badblock markers */
> + /* 4 bytes at offset 8 hold BBT header */
> + /* 1 byte at offset 12 holds BBT version */
> + /* 8 bytes at offset 16 hold JFFS2 clean markers */
> + 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
> + 34, 35, 36, 37, 38, 39, 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 = {
> + {.offset = 16, .length = 8, },
why not offset = 2, length = 22
Won't the badblock marker show if this is used as a BBT?
Can JFFS2 not use the same bytes when not a BBT?
> + {.offset = 64, },
You can kill the above line.
> + },
> +};
> +
> +/* An ECC layout for using 4-bit ECC with large-page (4096bytes) flash,
> + * storing ten ECC bytes plus the manufacturer's bad block marker byte,
> + * and not overlapping the default BBT markers.
> + */
> +static struct nand_ecclayout hwecc4_4096 __initconst = {
> + .eccbytes = 80,
> + .eccpos = { /* 2 bytes at offset 0 hold the badblock markers */
> + /* 4 bytes at offset 8 hold BBT header */
> + /* 1 byte at offset 12 holds BBT version */
> + /* 8 bytes at offset 16 hold JFFS2 clean markers */
> + 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
> + 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,
> + 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
> + 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
> + 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,
> + 74, 75, 76, 77, 78, 69, 80, 81, 82, 83,
> + 84, 85, 86, 87, 88, 89, 90, 91, 92, 93,
> + 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, },
Can these not be at the end??? i.e. 48-127
> + .oobfree = {
> + {.offset = 16, .length = 8, },
> + {.offset = 104, },
> + },
> +};
>
> static int __init nand_davinci_probe(struct platform_device *pdev)
> {
> @@ -689,15 +732,23 @@ static int __init nand_davinci_probe(struct platform_device *pdev)
> info->mtd.oobsize - 16;
> goto syndrome_done;
> }
> + if (chunks == 4) {
> + info->ecclayout = hwecc4_2048;
> + info->ecclayout.oobfree[1].length = info->mtd.oobsize -
> + info->ecclayout.oobfree[1].offset;
This can be removed, it is already 0.
> + info->chip.ecc.mode = NAND_ECC_HW_OOB_FIRST;
> + goto syndrome_done;
> + }
> + if (chunks == 8) {
> + info->ecclayout = hwecc4_4096;
> + info->ecclayout.oobfree[1].length = info->mtd.oobsize -
> + info->ecclayout.oobfree[1].offset;
> + info->chip.ecc.mode = NAND_ECC_HW_OOB_FIRST;
> + goto syndrome_done;
> + }
>
> - /* For large page chips we'll be wanting to use a
> - * not-yet-implemented mode that reads OOB data
> - * before reading the body of the page, to avoid
> - * the "infix OOB" model of NAND_ECC_HW_SYNDROME
> - * (and preserve manufacturer badblock markings).
> - */
> dev_warn(&pdev->dev, "no 4-bit ECC support yet "
> - "for large page NAND\n");
> + "for >4K page NAND\n");
> ret = -EIO;
> goto err_scan;
>
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