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

[Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

On Tue, 30 Aug 2016 11:02:12 +0800
<rogercc.lin-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> wrote:

> From: RogerCC Lin <rogercc.lin-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> 
> 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-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> ---
>  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;