[PATCH v4 2/2] mtd: rawnand: brcmnand: improve hamming oob layout

Álvaro Fernández Rojas
2020-05-12T07:57:46Z

The current code generates 8 oob sections:
S1 1-5
ECC 6-8
S2 9-15
S3 16-21
ECC 22-24
S4 25-31
S5 32-37
ECC 38-40
S6 41-47
S7 48-53
ECC 54-56
S8 57-63

Change it by merging continuous sections:
S1 1-5
ECC 6-8
S2 9-21
ECC 22-24
S3 25-37
ECC 38-40
S4 41-53
ECC 54-56
S5 57-63

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
v4: clarify small/large pages comment
v3: invert patch order
v2: keep original comment and fix correctly skip byte 6 for small-page nand

drivers/mtd/nand/raw/brcmnand/brcmnand.c | 35 +++++++++++-------------
1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index 1c1070111ebc..6292fac6cc4f 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -1100,33 +1100,30 @@ static int brcmnand_hamming_ooblayout_free(struct mtd_info *mtd, int section,
struct brcmnand_cfg *cfg = &host->hwcfg;
int sas = cfg->spare_area_size << cfg->sector_size_1k;
int sectors = cfg->page_size / (512 << cfg->sector_size_1k);
+ u32 next;

- if (section >= sectors * 2)
+ if (section > sectors)
return -ERANGE;

- oobregion->offset = (section / 2) * sas;
+ next = (section * sas);
+ if (section < sectors)
+ next += 6;

- if (section & 1) {
- oobregion->offset += 9;
- oobregion->length = 7;
+ if (section) {
+ oobregion->offset = ((section - 1) * sas) + 9;
} else {
- oobregion->length = 6;
-
- /* First sector of each page may have BBI */
- if (!section) {
- /*
- * Small-page NAND use byte 6 for BBI while large-page
- * NAND use bytes 0 and 1.
- */
- if (cfg->page_size > 512) {
- oobregion->offset += 2;
- oobregion->length -= 2;
- } else {
- oobregion->length--;
- }
+ if (cfg->page_size > 512) {
+ /* Large page NAND uses first 2 bytes for BBI */
+ oobregion->offset = 2;
+ } else {
+ /* Small page NAND uses last byte before ECC for BBI */
+ oobregion->offset = 0;
+ next--;
}
}

+ oobregion->length = next - oobregion->offset;
+
return 0;
}

--
2.26.2