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

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Message-Id: <20200512075733.745374-3-noltari@gmail.com>
Date:   Tue, 12 May 2020 09:57:33 +0200
From:   Álvaro Fernández Rojas 
        <noltari@...il.com>
To:     computersforpeace@...il.com, kdasu.kdev@...il.com,
        miquel.raynal@...tlin.com, richard@....at, vigneshr@...com,
        sumit.semwal@...aro.org, linux-mtd@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org
Cc:     Álvaro Fernández Rojas 
        <noltari@...il.com>
Subject: [PATCH v4 2/2] mtd: rawnand: brcmnand: improve hamming oob layout

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@...il.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