linux-kernel - [PATCH v0] mtd: rawnand: marvell: fix 8bit ECC layouts

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Message-ID: <20251022013752.2381694-1-aryan.srivastava@alliedtelesis.co.nz>
Date: Wed, 22 Oct 2025 14:37:52 +1300
From: Aryan Srivastava <aryan.srivastava@...iedtelesis.co.nz>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Aryan Srivastava <aryan.srivastava@...iedtelesis.co.nz>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>,
	Elad Nachman <enachman@...vell.com>,
	linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v0] mtd: rawnand: marvell: fix 8bit ECC layouts

These were modified to appease a check in nand_scan_tail. This change led
to the last spare bytes never being written to or read from.

Modify the fix by restoring the layouts and setting ecc->steps to the
full_chunk_cnt value in the 8 bit ECC cases (4k and 8k page size). This
allows the driver to continue reading/writing all chunks while also
passing the check in nand_scan_tail.

Fixes: e6a30d0c48a1 ("mtd: rawnand: marvell: fix layouts")
Signed-off-by: Aryan Srivastava <aryan.srivastava@...iedtelesis.co.nz>
---
 drivers/mtd/nand/raw/marvell_nand.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/marvell_nand.c b/drivers/mtd/nand/raw/marvell_nand.c
index 303b3016a070..c20feacbaca8 100644
--- a/drivers/mtd/nand/raw/marvell_nand.c
+++ b/drivers/mtd/nand/raw/marvell_nand.c
@@ -292,10 +292,10 @@ static const struct marvell_hw_ecc_layout marvell_nfc_layouts[] = {
 	MARVELL_LAYOUT( 2048,   512,  8,  2,  1, 1024,  0, 30,1024,64, 30),
 	MARVELL_LAYOUT( 2048,   512,  16, 4,  4, 512,   0, 30,  0, 32, 30),
 	MARVELL_LAYOUT( 4096,   512,  4,  2,  2, 2048, 32, 30,  0,  0,  0),
-	MARVELL_LAYOUT( 4096,   512,  8,  4,  4, 1024,  0, 30,  0, 64, 30),
+	MARVELL_LAYOUT( 4096,   512,  8,  5,  4, 1024,  0, 30,  0, 64, 30),
 	MARVELL_LAYOUT( 4096,   512,  16, 8,  8, 512,   0, 30,  0, 32, 30),
 	MARVELL_LAYOUT( 8192,   512,  4,  4,  4, 2048,  0, 30,  0,  0,  0),
-	MARVELL_LAYOUT( 8192,   512,  8,  8,  8, 1024,  0, 30,  0, 160, 30),
+	MARVELL_LAYOUT( 8192,   512,  8,  9,  8, 1024,  0, 30,  0, 160, 30),
 	MARVELL_LAYOUT( 8192,   512,  16, 16, 16, 512,  0, 30,  0,  32, 30),
 };
 
@@ -2286,7 +2286,16 @@ static int marvell_nand_hw_ecc_controller_init(struct mtd_info *mtd,
 	}
 
 	mtd_set_ooblayout(mtd, &marvell_nand_ooblayout_ops);
-	ecc->steps = l->nchunks;
+
+	/* Validity checks in nand_scan_tail assume even sized chunks, but in the case of 8bit
+	 * ECC with 4k/8k page size the last chunk is spare data, which is not sized to the data
+	 * chunks. Overwrite the ecc->steps to pass this validity check, while maintaining the
+	 * correct number of chunks in-driver.
+	 */
+	if (ecc->strength == 8 && mtd->writesize > SZ_2K)
+		ecc->steps = l->full_chunk_cnt;
+	else
+		ecc->steps = l->nchunks;
 	ecc->size = l->data_bytes;
 
 	if (ecc->strength == 1) {
-- 
2.51.0