Re: [RESEND PATCH V2 2/2] mtd: core: NAND filling block

Boris Brezillon
2019-01-20T17:37:12Z

On Fri, 18 Jan 2019 22:12:04 +0000
"Bean Huo (beanhuo)" <beanhuo@micron.com> wrote:

> +static int check_page_if_emtpy(struct nand_chip *chip, char *data)
> +{
> + struct mtd_info *mtd = nand_to_mtd(chip);
> + int ret, i;
> + void *databuf, *eccbuf;
> + int max_bitflips;
> + struct mtd_oob_region oobregion;
> +
> + mtd_ooblayout_ecc(mtd, 0, &oobregion);
> + eccbuf = chip->oob_poi + oobregion.offset;
> + databuf = data;
> + max_bitflips = 0;
> +
> + for (i = 0; i < chip->ecc.steps; i++) {
> + ret = nand_check_erased_ecc_chunk(data,
> + chip->ecc.size,
> + eccbuf,
> + chip->ecc.bytes,
> + NULL, 0,
> + chip->ecc.strength);
> + if (ret >= 0)
> + max_bitflips = max(ret, max_bitflips);
> + else
> + return false;
> +
> + databuf += chip->ecc.size;
> + eccbuf += chip->ecc.bytes;
> +
> + }

You should check the whole page and not only in-band-data+ECC bytes.
Plus, the "overwrite page" trigger is not dependent on the ECC
strength, but more something related to the NAND chip itself so using
ecc->strength as a threshold sounds like a bad idea to me.