linux-kernel - [PATCH 3/3] mtd: nand: sunxi: Support ECC maximization

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Message-Id: <1465397926-7904-4-git-send-email-boris.brezillon@free-electrons.com>
Date:	Wed,  8 Jun 2016 16:58:46 +0200
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	linux-mtd@...ts.infradead.org,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Richard Weinberger <richard@....at>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] mtd: nand: sunxi: Support ECC maximization

Setup the maximum ECC config when NAND_ECC_MAXIMIZE is set.

Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
---
 drivers/mtd/nand/sunxi_nand.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index 8dfcb65..21dad0b 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1814,6 +1814,35 @@ static int sunxi_nand_hw_common_ecc_ctrl_init(struct mtd_info *mtd,
 	if (!data)
 		return -ENOMEM;
 
+	if (ecc->options & NAND_ECC_MAXIMIZE) {
+		int bytes;
+
+		ecc->size = 1024;
+		nsectors = mtd->writesize / ecc->size;
+
+		/* Reserve 2 bytes for the BBM */
+		bytes = (mtd->oobsize - 2) / nsectors;
+
+		/* 4 non-ECC bytes are added before each ECC bytes section */
+		bytes -= 4;
+
+		/* and bytes has to be even. */
+		if (bytes % 2)
+			bytes--;
+
+		ecc->strength = bytes * 8 / fls(8 * ecc->size);
+
+		for (i = 0; i < ARRAY_SIZE(strengths); i++) {
+			if (strengths[i] > ecc->strength)
+				break;
+		}
+
+		if (!i)
+			ecc->strength = 0;
+		else
+			ecc->strength = strengths[i - 1];
+	}
+
 	if (ecc->size != 512 && ecc->size != 1024)
 		return -EINVAL;
 
-- 
2.7.4