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mtd: nand: Request strength instead of bytes for soft BCH 

Previously, we requested that drivers pass ecc.size and ecc.bytes when
using NAND_ECC_SOFT_BCH. However, a driver is likely to only know the ECC
strength required for its NAND, so each driver would need to perform a
strength-to-bytes calculation.

Avoid duplicating this calculation in each driver by asking drivers to
pass ecc.size and ecc.strength so that the strength-to-bytes calculation
need only be implemented once.

This reverts/generalizes this commit:
    mtd: nand: Base BCH ECC bytes on required strength

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Aaron Sierra 2015-01-14 17:41:31 -06:00 committed by Brian Norris
parent 240181fd0f
commit e0377cdeba
3 changed files with 9 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/mtd/nand/nand_base.c
View File

@ -4037,22 +4037,24 @@ int nand_scan_tail(struct mtd_info *mtd)
ecc->read_oob = nand_read_oob_std;
ecc->write_oob = nand_write_oob_std;
/*
* Board driver should supply ecc.size and ecc.bytes values to
* select how many bits are correctable; see nand_bch_init()
* for details. Otherwise, default to 4 bits for large page
* devices.
* Board driver should supply ecc.size and ecc.strength values
* to select how many bits are correctable. Otherwise, default
* to 4 bits for large page devices.
*/
if (!ecc->size && (mtd->oobsize >= 64)) {
ecc->size = 512;
ecc->bytes = DIV_ROUND_UP(13 * ecc->strength, 8);
ecc->strength = 4;
}
/* See nand_bch_init() for details. */
ecc->bytes = DIV_ROUND_UP(
ecc->strength * fls(8 * ecc->size), 8);
ecc->priv = nand_bch_init(mtd, ecc->size, ecc->bytes,
&ecc->layout);
if (!ecc->priv) {
pr_warn("BCH ECC initialization failed!\n");
BUG();
}
ecc->strength = ecc->bytes * 8 / fls(8 * ecc->size);
break;
case NAND_ECC_NONE:

1
drivers/mtd/nand/nandsim.c
View File

@ -2337,6 +2337,7 @@ static int __init ns_init_module(void)
}
chip->ecc.mode = NAND_ECC_SOFT_BCH;
chip->ecc.size = 512;
chip->ecc.strength = bch;
chip->ecc.bytes = eccbytes;
NS_INFO("using %u-bit/%u bytes BCH ECC\n", bch, chip->ecc.size);
}

2
drivers/mtd/nand/sunxi_nand.c
View File

@ -1110,8 +1110,6 @@ static int sunxi_nand_ecc_init(struct mtd_info *mtd, struct nand_ecc_ctrl *ecc,
switch (ecc->mode) {
case NAND_ECC_SOFT_BCH:
ecc->bytes = DIV_ROUND_UP(ecc->strength * fls(8 * ecc->size),
8);
break;
case NAND_ECC_HW:
ret = sunxi_nand_hw_ecc_ctrl_init(mtd, ecc, np);