linux-kernel - [PATCH] nand: brcmnand: correctly verify erased pages

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Message-Id: <20200504092943.2739784-1-noltari@gmail.com>
Date:   Mon,  4 May 2020 11:29:43 +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] nand: brcmnand: correctly verify erased pages

The current code checks that the whole OOB area is erased.
This is a problem when JFFS2 cleanmarkers are added to the OOB, since it will
fail due to the usable OOB bytes not being 0xff.
Correct this by only checking that the ECC aren't 0xff.

Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
---
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index e4e3ceeac38f..546f0807b887 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -2018,6 +2018,7 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
 static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,
 		  struct nand_chip *chip, void *buf, u64 addr)
 {
+	struct mtd_oob_region oobecc;
 	int i, sas;
 	void *oob = chip->oob_poi;
 	int bitflips = 0;
@@ -2035,11 +2036,24 @@ static int brcmstb_nand_verify_erased_page(struct mtd_info *mtd,
 	if (ret)
 		return ret;
 
-	for (i = 0; i < chip->ecc.steps; i++, oob += sas) {
+	for (i = 0; i < chip->ecc.steps; i++) {
 		ecc_chunk = buf + chip->ecc.size * i;
-		ret = nand_check_erased_ecc_chunk(ecc_chunk,
-						  chip->ecc.size,
-						  oob, sas, NULL, 0,
+
+		ret = nand_check_erased_ecc_chunk(ecc_chunk, chip->ecc.size,
+						  NULL, 0, NULL, 0,
+						  chip->ecc.strength);
+		if (ret < 0)
+			return ret;
+
+		bitflips = max(bitflips, ret);
+	}
+
+	for (i = 0; mtd->ooblayout->ecc(mtd, i, &oobecc) != -ERANGE; i++)
+	{
+		ret = nand_check_erased_ecc_chunk(NULL, 0,
+						  oob + oobecc.offset,
+						  oobecc.length,
+						  NULL, 0,
 						  chip->ecc.strength);
 		if (ret < 0)
 			return ret;
-- 
2.26.2