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>

3 files changed, 9 insertions, 8 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 3f24b587304f..f6af96926f00 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -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:
diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c
index a8fa8dad9b23..f2324271b94e 100644
--- a/drivers/mtd/nand/nandsim.c
+++ b/drivers/mtd/nand/nandsim.c
@@ -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);
         }
diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index ccaa8e283388..6f93b2990d25 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -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);