mtd: nand: fix chances to create incomplete ECC data when writing

When mtk_nfc_do_write_page() comparing the sector number,because the
sector number field is at the 12th-bit position of NFI_BYTELEN
register,the masked register should be shifted 12 bits before being
compared.The result of this bug may cause the second subpage has
incomplete ECC parity bytes.
Signed-off-by: RogerCC Lin <rogercc.lin@mediatek.com>
Fixes: 1d6b1e46 ("mtd: mediatek: driver for MTK Smart Device")
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/mtk_nand.c

@@ -93,6 +93,9 @@
 #define		NFI_FSM_MASK		(0xf << 16)
 #define NFI_ADDRCNTR		(0x70)
 #define		CNTR_MASK		GENMASK(16, 12)
+#define		ADDRCNTR_SEC_SHIFT	(12)
+#define		ADDRCNTR_SEC(val) \
+		(((val) & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT)
 #define NFI_STRADDR		(0x80)
 #define NFI_BYTELEN		(0x84)
 #define NFI_CSEL		(0x90)
@@ -699,7 +702,7 @@ static int mtk_nfc_do_write_page(struct mtd_info *mtd, struct nand_chip *chip,
 	}
 
 	ret = readl_poll_timeout_atomic(nfc->regs + NFI_ADDRCNTR, reg,
-					(reg & CNTR_MASK) >= chip->ecc.steps,
+					ADDRCNTR_SEC(reg) >= chip->ecc.steps,
 					10, MTK_TIMEOUT);
 	if (ret)
 		dev_err(dev, "hwecc write timeout\n");
@@ -902,7 +905,7 @@ static int mtk_nfc_read_subpage(struct mtd_info *mtd, struct nand_chip *chip,
 		dev_warn(nfc->dev, "read ahb/dma done timeout\n");
 
 	rc = readl_poll_timeout_atomic(nfc->regs + NFI_BYTELEN, reg,
-				       (reg & CNTR_MASK) >= sectors, 10,
+				       ADDRCNTR_SEC(reg) >= sectors, 10,
 				       MTK_TIMEOUT);
 	if (rc < 0) {
 		dev_err(nfc->dev, "subpage done timeout\n");