+Yoshi
Hi Miquel,
Subject prefix should be "mtd: nand: " in lowercase.
Le Wed, 16 Aug 2017 09:39:06 +0200,
Miquel Raynal <miquel.ray...@free-electrons.com> a écrit :
> Add layout functions for small and large pages with mainly free bytes
> plus reserved space for Bad Block Markers. This may be useful for
> specific chip that use on-die ECC feature, ie. the TOSHIBA BENAND
> (Built-in ECC NAND). The ECC bytes are stored in an isolated area
> inaccessible by the driver and thus the OOB layout must only reserve
> space for Bad Block Markers.
Yes, that's true, but as said below, I expect the toshiba driver to
explicitly set this layout.
>
> Bad Block Markers position was extracted from the existing OOB layouts
> by assigning as free all the bytes marked as ECC.
>
> The layout functions added by this patch were supposed to be used with
> ECC_NONE mode but it would break existing drivers that do not rely on
> an implementation of this layout by the core, so set it as a fallthrough
> when no other layout matches.
Well, it's still supposed to be used when ECC_NONE is set, except we can
only use it for cases that were not already falling in the supported
large/small page with ECC cases.
>
> Signed-off-by: Miquel Raynal <miquel.ray...@free-electrons.com>
> ---
> drivers/mtd/nand/nand_base.c | 65
> ++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 60 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index c5221795a1e8..7c0ae674e50a 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -53,7 +53,38 @@ static int nand_get_device(struct mtd_info *mtd, int
> new_state);
> static int nand_do_write_oob(struct mtd_info *mtd, loff_t to,
> struct mtd_oob_ops *ops);
>
> -/* Define default oob placement schemes for large and small page devices */
> +/*
> + * Define default OOB placement schemes for:
> + * - no ECC or software ECC
> + * - small or large page devices
> + */
> +static int nand_ooblayout_free_sp_no_ecc(struct mtd_info *mtd, int section,
> + struct mtd_oob_region *oobregion)
> +{
> + if (section > 1)
> + return -ERANGE;
> +
> + if (!section) {
> + if (mtd->oobsize == 16) {
> + oobregion->offset = 0;
> + oobregion->length = 4;
> + } else {
> + oobregion->offset = 0;
> + oobregion->length = 5;
> + }
> + } else {
> + oobregion->offset = 6;
> + oobregion->length = mtd->oobsize - oobregion->offset;
> + }
> +
> + return 0;
> +}
> +
> +const struct mtd_ooblayout_ops nand_ooblayout_sp_no_ecc_ops = {
> + .free = nand_ooblayout_free_sp_no_ecc,
> +};
> +EXPORT_SYMBOL_GPL(nand_ooblayout_sp_no_ecc_ops);
> +
> static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section,
> struct mtd_oob_region *oobregion)
> {
> @@ -109,6 +140,23 @@ const struct mtd_ooblayout_ops nand_ooblayout_sp_ops = {
> };
> EXPORT_SYMBOL_GPL(nand_ooblayout_sp_ops);
>
> +static int nand_ooblayout_free_lp_no_ecc(struct mtd_info *mtd, int section,
> + struct mtd_oob_region *oobregion)
> +{
> + if (section)
> + return -ERANGE;
> +
> + oobregion->offset = 2;
> + oobregion->length = mtd->oobsize - oobregion->offset;
> +
> + return 0;
> +}
> +
> +const struct mtd_ooblayout_ops nand_ooblayout_lp_no_ecc_ops = {
> + .free = nand_ooblayout_free_lp_no_ecc,
> +};
> +EXPORT_SYMBOL_GPL(nand_ooblayout_lp_no_ecc_ops);
No need to export those symbols until someone really needs them.
BTW, they are exported but not declared in nand.h, so right now nobody can
use them.
> +
> static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section,
> struct mtd_oob_region *oobregion)
> {
> @@ -4649,10 +4697,17 @@ int nand_scan_tail(struct mtd_info *mtd)
> mtd_set_ooblayout(mtd, &nand_ooblayout_lp_hamming_ops);
> break;
> default:
> - WARN(1, "No oob scheme defined for oobsize %d\n",
> - mtd->oobsize);
> - ret = -EINVAL;
> - goto err_free;
> + /*
> + * In the case of on-die ECC (when ECC are stored in an
> + * isolated area inaccessible by the driver), the OOB
> + * layout must only reserve space for Bad Block Markers.
> + */
This kind of on-die ECC is not yet supported and I'd expect NAND
manufacturer drivers to set the appropriate layout before reaching this
point, so that's not really relevant here.
> + if (mtd->writesize <= 512)
> + mtd_set_ooblayout(mtd,
> + &nand_ooblayout_sp_no_ecc_ops);
> + else
> + mtd_set_ooblayout(mtd,
> + &nand_ooblayout_lp_no_ecc_ops);
That's not exactly what I was suggesting. What I had in mind was:
if (ecc->mode == NAND_ECC_NONE) {
/*
* Expose the whole OOB area to users if
ECC_NONE
* is passed. We could do that for all kind of
* ->oobsize, but we must keep the old
* large/small page with ECC layout for
* compatibility reasons.
*/
if (mtd->writesize <= 512)
mtd_set_ooblayout(mtd,
&nand_ooblayout_sp_no_ecc_ops);
else
mtd_set_ooblayout(mtd,
&nand_ooblayout_lp_no_ecc_ops);
break;
}
WARN(1, "No oob scheme defined for oobsize %d\n",
mtd->oobsize);
ret = -EINVAL;
goto err_free;
> }
> }
>
