[PATCH v3 0/2] mtd: nand: fix writing incorrect ECC data in OOB region

[PATCH v3 0/2] mtd: nand: fix writing incorrect ECC data in OOB region

[rogercc.lin]

From: RogerCC Lin <rogercc.lin@mediatek.com>

This series fix chances to write incorrect ECC data which may cause uncorrectable ECC error when reading.

changes since v2:
- use macro for shift operation.

changes since v1:
- separate patches into 2.
- use shift operator with byte access to avoid endianness conversion problems.
- follow linux coding style.

The patch passed the test of UBIFS file-system read/write on Mediatek's RFB. The tested driver is checked-out from LEDE OpenWRT project's upstream driver, which is pretty much same as nand/next branch upstream driver(git clone https://git.lede-project.org/source.git).

RogerCC Lin (2):
  mtd: nand: fix generating over-boundary ECC data when writing.
  mtd: nand: fix chances to create incomplete ECC data when writing.

 drivers/mtd/nand/mtk_ecc.c  |   12 ++++++++----
 drivers/mtd/nand/mtk_nand.c |    9 +++++----
 2 files changed, 13 insertions(+), 8 deletions(-)

[PATCH v3 1/2] mtd: nand: fix generating over-boundary ECC data when writing

[rogercc.lin]

From: RogerCC Lin <rogercc.lin@mediatek.com>

When mtk_ecc_encode() is writing the ECC parity data to the OOB
region,because each register is 4 bytes in length,but the len's unit is
in bytes,the operation in the for loop will cross the ECC's boundary.

Signed-off-by: RogerCC Lin <rogercc.lin@mediatek.com>
---
 drivers/mtd/nand/mtk_ecc.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/mtk_ecc.c b/drivers/mtd/nand/mtk_ecc.c
index 25a4fbd..495538e 100644
--- a/drivers/mtd/nand/mtk_ecc.c
+++ b/drivers/mtd/nand/mtk_ecc.c
@@ -366,7 +366,8 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config,
 		   u8 *data, u32 bytes)
 {
 	dma_addr_t addr;
-	u32 *p, len, i;
+	u8 *p;
+	u32 len, i, val;
 	int ret = 0;
 
 	addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE);
@@ -392,11 +393,14 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config,
 
 	/* Program ECC bytes to OOB: per sector oob = FDM + ECC + SPARE */
 	len = (config->strength * ECC_PARITY_BITS + 7) >> 3;
-	p = (u32 *)(data + bytes);
+	p = data + bytes;
 
 	/* write the parity bytes generated by the ECC back to the OOB region */
-	for (i = 0; i < len; i++)
-		p[i] = readl(ecc->regs + ECC_ENCPAR(i));
+	for (i = 0; i < len; i++) {
+		if ((i % 4) == 0)
+			val = readl(ecc->regs + ECC_ENCPAR(i >> 2));
+		p[i] = (val >> ((i % 4) * 8)) & 0xff;
+	}
 timeout:
 
 	dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
-- 
1.7.0.4

[PATCH v3 2/2] mtd: nand: fix chances to create incomplete ECC data when writing

[rogercc.lin]

From: RogerCC Lin <rogercc.lin@mediatek.com>

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>
---
 drivers/mtd/nand/mtk_nand.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/mtk_nand.c b/drivers/mtd/nand/mtk_nand.c
index ddaa2ac..260bd20 100644
--- a/drivers/mtd/nand/mtk_nand.c
+++ b/drivers/mtd/nand/mtk_nand.c
@@ -93,6 +93,7 @@
 #define		NFI_FSM_MASK		(0xf << 16)
 #define NFI_ADDRCNTR		(0x70)
 #define		CNTR_MASK		GENMASK(16, 12)
+#define		ADDRCNTR_SEC_SHIFT	(12)
 #define NFI_STRADDR		(0x80)
 #define NFI_BYTELEN		(0x84)
 #define NFI_CSEL		(0x90)
@@ -699,8 +700,8 @@ 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,
-					10, MTK_TIMEOUT);
+		((reg & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT) >= chip->ecc.steps,
+		10, MTK_TIMEOUT);
 	if (ret)
 		dev_err(dev, "hwecc write timeout\n");
 
@@ -902,8 +903,8 @@ 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,
-				       MTK_TIMEOUT);
+		((reg & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT) >= sectors,
+		10, MTK_TIMEOUT);
 	if (rc < 0) {
 		dev_err(nfc->dev, "subpage done timeout\n");
 		bitflips = -EIO;
-- 
1.7.0.4

Re: [PATCH v3 2/2] mtd: nand: fix chances to create incomplete ECC data when writing

[Boris Brezillon]

On Tue, 30 Aug 2016 11:02:12 +0800
<rogercc.lin@mediatek.com> wrote:

> From: RogerCC Lin <rogercc.lin@mediatek.com>
> 
> 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>
> ---
>  drivers/mtd/nand/mtk_nand.c |    9 +++++----
>  1 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mtd/nand/mtk_nand.c b/drivers/mtd/nand/mtk_nand.c
> index ddaa2ac..260bd20 100644
> --- a/drivers/mtd/nand/mtk_nand.c
> +++ b/drivers/mtd/nand/mtk_nand.c
> @@ -93,6 +93,7 @@
>  #define		NFI_FSM_MASK		(0xf << 16)
>  #define NFI_ADDRCNTR		(0x70)
>  #define		CNTR_MASK		GENMASK(16, 12)
> +#define		ADDRCNTR_SEC_SHIFT	(12)

While you're at it, define

#define			ADDRCNTR_SEC(val)	\
			(((val) & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT)

>  #define NFI_STRADDR		(0x80)
>  #define NFI_BYTELEN		(0x84)
>  #define NFI_CSEL		(0x90)
> @@ -699,8 +700,8 @@ 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,
> -					10, MTK_TIMEOUT);
> +		((reg & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT) >= chip->ecc.steps,

and use it here
				ADDRCNTR_SEC(reg) >= chip->ecc.steps

> +		10, MTK_TIMEOUT);
>  	if (ret)
>  		dev_err(dev, "hwecc write timeout\n");
>  
> @@ -902,8 +903,8 @@ 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,
> -				       MTK_TIMEOUT);
> +		((reg & CNTR_MASK) >> ADDRCNTR_SEC_SHIFT) >= sectors,
> +		10, MTK_TIMEOUT);
>  	if (rc < 0) {
>  		dev_err(nfc->dev, "subpage done timeout\n");
>  		bitflips = -EIO;