mtd: nand: Support maximizing ECC when using software BCH

Add support for ECC maximization when software BCH with
nand_ooblayout_lp_ops layout is used.
Other cases should be handled by the NAND controller driver.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 6669dfcf9e794e1d9727bb6e58097fdb5ac7e65a..a74d9e4bd8b2ad3db2b776d942b8e294f917a056 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -4396,6 +4396,7 @@ static int nand_set_ecc_soft_ops(struct mtd_info *mtd)
                ecc->write_page_raw = nand_write_page_raw;
                ecc->read_oob = nand_read_oob_std;
                ecc->write_oob = nand_write_oob_std;
+
                /*
                * Board driver should supply ecc.size and ecc.strength
                * values to select how many bits are correctable.
@@ -4418,6 +4419,25 @@ static int nand_set_ecc_soft_ops(struct mtd_info *mtd)
                        }
 
                        mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
+
+               }
+
+               /*
+                * We can only maximize ECC config when the default layout is
+                * used, otherwise we don't know how many bytes can really be
+                * used.
+                */
+               if (mtd->ooblayout == &nand_ooblayout_lp_ops &&
+                   ecc->options & NAND_ECC_MAXIMIZE) {
+                       int steps, bytes;
+
+                       /* Always prefer 1k blocks over 512bytes ones */
+                       ecc->size = 1024;
+                       steps = mtd->writesize / ecc->size;
+
+                       /* Reserve 2 bytes for the BBM */
+                       bytes = (mtd->oobsize - 2) / steps;
+                       ecc->strength = bytes * 8 / fls(8 * ecc->size);
                }
 
                /* See nand_bch_init() for details. */