linux-kernel - [PATCH 1/2] nand: brcmnand: improve hamming oob layout

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Message-Id: <20200504093034.2739968-1-noltari@gmail.com>
Date:   Mon,  4 May 2020 11:30:33 +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 1/2] nand: 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>
---
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 28 +++++++++---------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index e4e3ceeac38f..1bba309c7684 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -1100,29 +1100,21 @@ 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;
-	} else {
-		oobregion->length = 6;
+	if (section)
+		oobregion->offset = ((section - 1) * sas) + 9;
+	else
+		oobregion->offset = 1; /* BBI */
 
-		/* First sector of each page may have BBI */
-		if (!section) {
-			/*
-			 * Small-page NAND use byte 6 for BBI while large-page
-			 * NAND use byte 0.
-			 */
-			if (cfg->page_size > 512)
-				oobregion->offset++;
-			oobregion->length--;
-		}
-	}
+	oobregion->length = next - oobregion->offset;
 
 	return 0;
 }
-- 
2.26.2