Re: [PATCH v3 2/4] mtd: rawnand: gpmi: Add strict ecc strength check

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Han,

han.xu@nxp.com wrote on Mon,  4 Apr 2022 14:54:25 -0500:

> Add strict ecc strength check in gpmi_check_ecc() function, which is
> same as nand_ecc_is_strong_enough() did. It will check both correct bits
> and correct bits per byte to ensure it meets chip required ecc strength.
> 
> Signed-off-by: Han Xu <han.xu@nxp.com>
> 
> ---
> Changes since v2:
>  - split the ecc check to a single patch
> ---
> ---
>  drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 24 ++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> index 4144d5937103..9a37f8cc663e 100644
> --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> @@ -238,9 +238,14 @@ static void gpmi_dump_info(struct gpmi_nand_data *this)
>  		geo->block_mark_bit_offset);
>  }
>  
> -static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
> +static bool gpmi_check_ecc(struct gpmi_nand_data *this)

This change should be in a separate commit.

>  {
> +	struct nand_chip *chip = &this->nand;
> +	struct mtd_info *mtd = nand_to_mtd(&this->nand);
>  	struct bch_geometry *geo = &this->bch_geometry;
> +	const struct nand_ecc_props *requirements =
> +		nanddev_get_ecc_requirements(&chip->base);
> +	int corr, ds_corr;
>  
>  	/* Do the sanity check. */
>  	if (GPMI_IS_MXS(this)) {
> @@ -248,7 +253,22 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
>  		if (geo->gf_len == 14)
>  			return false;
>  	}
> -	return geo->ecc_strength <= this->devdata->bch_max_ecc_strength;
> +
> +	if (geo->ecc_strength > this->devdata->bch_max_ecc_strength)
> +		return false;
> +
> +	/* check ecc strength, same as nand_ecc_is_strong_enough() did */

Why not using nand_ecc_is_strong_enough() in this case?

> +	if (requirements->step_size) {
> +		corr = mtd->writesize * geo->ecc_strength /
> +		       geo->ecc_chunk_size;
> +		ds_corr = mtd->writesize * requirements->strength /
> +			  requirements->step_size;
> +		if (corr < ds_corr ||
> +		    geo->ecc_strength < requirements->strength)
> +			return false;
> +	}
> +
> +	return true;
>  }
>  
>  /*


Thanks,
Miquèl

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