[PATCH] mtd/nand: don't use {read,write}_buf for 8-bit transfers

[Huang Shijie]

于 2013年02月27日 23:10, Uwe Kleine-König 写道:
> According to the Open NAND Flash Interface Specification (ONFI) Revision
> 3.1 "Parameters are always transferred on the lower 8-bits of the data
> bus." for the Get Features and Set Features commands.
>
> So using read_buf and write_buf is wrong for 16-bit wide nand chips as
> they use I/O[15:0]. The Get Features command is easily fixed using 4
> times the read_byte callback. For Set Features error out as there is no
> write_byte callback.
>
> Signed-off-by: Uwe Kleine-König<u.kleine-koenig at pengutronix.de>
> ---
> Hello,
>
> note this is only compile tested and I don't have a 16-bit wide nand, so I
> don't even saw a failure.
>
> The problem exists since commit
>
> 	7db03ec (mtd: add helpers to set/get features for ONFI nand)
>
> which introduced the two functions.
>
> Still I'd like to know how I can write a byte (or a sequence of bytes) as this
> is necessary for locking the otp are of micron chips. Well, I could implement
> it for 8-bit chips only, but this isn't very satisfying.
>
> Do we need to add a write_byte callback to struct nand_chip? Or is there
> a way to do write a byte that I'm just too blind to see?
>
> Is this patch relevant for stable? Probably not!?
>
> Best regards
> Uwe
>
>   drivers/mtd/nand/nand_base.c |   14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 4321415..abfd8ca 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2706,7 +2706,7 @@ static int nand_block_markbad(struct mtd_info *mtd, loff_t ofs)
>   }
>
>   /**
> - * nand_onfi_set_features- [REPLACEABLE] set features for ONFI nand
> + * nand_onfi_set_features - [REPLACEABLE] set features for ONFI nand
>    * @mtd: MTD device structure
>    * @chip: nand chip info structure
>    * @addr: feature address.
> @@ -2720,6 +2720,11 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip,
>   	if (!chip->onfi_version)
>   		return -EINVAL;
>
> +	if (chip->options&  NAND_BUSWIDTH_16) {
> +		pr_warn("onfi set feature command buggy for 16-bit chips\n");
> +		return -ENOTSUPP;
> +	}
> +
>   	chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES, addr, -1);
>   	chip->write_buf(mtd, subfeature_param, ONFI_SUBFEATURE_PARAM_LEN);
>   	status = chip->waitfunc(mtd, chip);
> @@ -2729,7 +2734,7 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip,
>   }
>
>   /**
> - * nand_onfi_get_features- [REPLACEABLE] get features for ONFI nand
> + * nand_onfi_get_features - [REPLACEABLE] get features for ONFI nand
>    * @mtd: MTD device structure
>    * @chip: nand chip info structure
>    * @addr: feature address.
> @@ -2738,6 +2743,8 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip,
>   static int nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip,
>   			int addr, uint8_t *subfeature_param)
>   {
> +	int i;
> +
>   	if (!chip->onfi_version)
>   		return -EINVAL;
>
> @@ -2745,7 +2752,8 @@ static int nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip,
>   	memset(subfeature_param, 0, ONFI_SUBFEATURE_PARAM_LEN);
>
>   	chip->cmdfunc(mtd, NAND_CMD_GET_FEATURES, addr, -1);
> -	chip->read_buf(mtd, subfeature_param, ONFI_SUBFEATURE_PARAM_LEN);
> +	for (i = 0; i<  ONFI_SUBFEATURE_PARAM_LEN; ++i)
> +		*subfeature_param++ = chip->read_byte(mtd);
>   	return 0;
>   }
>
Acked-by: Huang Shijie <b32955 at freescale.com>