On Thu, 24 Aug 2017 10:35:38 +0200 Miquel Raynal <[email protected]> wrote:
> Add layout functions for large pages with mainly free bytes > plus reserved space for Bad Block Markers. This may be useful for > configurations that does set ECC_NONE. Specific chips that use > on-die ECC feature, ie. the TOSHIBA BENAND (Built-in ECC NAND), > might also take advantage of it: 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. > > Bad block markers position was extracted from the existing OOB layouts > by assigning as free all the bytes marked as ECC. > > Normally, if NAND_ECC_NONE is chosen, the MTD user can use the whole OOB > area (except the bytes reserved for the bad block markers) to store > private data, but the NAND framework has been using the same OOB layout > (the one reserving ECC bytes) no matter whether ECC is enabled or not. > In order to not break existing MTD users which may rely on this layout > to work properly, we keep things unchanged and only use the 'no_ecc' > layouts for previously unsupported configurations. > > Signed-off-by: Miquel Raynal <[email protected]> > --- > drivers/mtd/nand/nand_base.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index c5221795a1e8..ef40866d3435 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -109,6 +109,22 @@ 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, > +}; > + > static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section, > struct mtd_oob_region *oobregion) > { > @@ -4649,6 +4665,19 @@ int nand_scan_tail(struct mtd_info *mtd) > mtd_set_ooblayout(mtd, &nand_ooblayout_lp_hamming_ops); > break; > default: > + /* > + * 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 when ->oobsize <= 128 for > + * compatibility reasons. > + */ > + if (ecc->mode == NAND_ECC_NONE) { > + mtd_set_ooblayout(mtd, > + &nand_ooblayout_lp_no_ecc_ops); Sorry again for not noticing that earlier but it seems nand_ooblayout_lp_no_ecc_ops is not needed. Indeed, when ecc->bytes = 0 (which is the case when ecc->mode = NAND_ECC_NONE) nand_ooblayout_lp_ops already exposes all OOB bytes as free. You can just re-use nand_ooblayout_lp_ops here. The only thing you might want to do is patch nand_ooblayout_ecc_lp() to return -ERANGE when ecc->total is 0 so that the MTD user does not end up with a 0 length OOB region.
