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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Miquel Raynal <miquel.raynal@free-electrons.com>
Subject: [PATCH 4.15 091/202] mtd: nand: sunxi: Fix ECC strength choice
Date:   Thu, 15 Feb 2018 16:16:31 +0100
Message-Id: <20180215151718.183130118@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miquel Raynal <miquel.raynal@free-electrons.com>

commit f4c6cd1a7f2275d5bc0e494b21fff26f8dde80f0 upstream.

When the requested ECC strength does not exactly match the strengths
supported by the ECC engine, the driver is selecting the closest
strength meeting the 'selected_strength > requested_strength'
constraint. Fix the fact that, in this particular case, ecc->strength
value was not updated to match the 'selected_strength'.

For instance, one can encounter this issue when no ECC requirement is
filled in the device tree while the NAND chip minimum requirement is not
a strength/step_size combo natively supported by the ECC engine.

Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller support")
Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/nand/sunxi_nand.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1853,8 +1853,14 @@ static int sunxi_nand_hw_common_ecc_ctrl
 
 	/* Add ECC info retrieval from DT */
 	for (i = 0; i < ARRAY_SIZE(strengths); i++) {
-		if (ecc->strength <= strengths[i])
+		if (ecc->strength <= strengths[i]) {
+			/*
+			 * Update ecc->strength value with the actual strength
+			 * that will be used by the ECC engine.
+			 */
+			ecc->strength = strengths[i];
 			break;
+		}
 	}
 
 	if (i >= ARRAY_SIZE(strengths)) {