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SubjectRe: [PATCH v2] mtd: nand: support for Toshiba BENAND (Built-in ECC NAND)
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On Thu, Jun 11, 2015 at 6:00 PM, KOBAYASHI Yoshitake
<yoshitake.kobayashi@toshiba.co.jp> wrote:
> This patch enables support for Toshiba BENAND.
> BENAND is a SLC NAND solution that automatically generates ECC inside
> NAND chip.
>
> Some of the comments in the following discussion may need to be considerd.
> https://lkml.org/lkml/2015/3/25/310

Yep.

> +void nand_benand_init(struct mtd_info *mtd)
> +{
> + struct nand_chip *chip = mtd->priv;
> +
> + pr_info("%s\n", __func__);

Please kill all these prints. Use ftrace to trace function calls.

> + chip->ecc.size = mtd->writesize;
> + chip->ecc.strength = 1;

BENAND can correct only one bit?
This would explain why you consider it as fast. ;-)

> +int nand_benand_status_chk(struct mtd_info *mtd, struct nand_chip *chip)
> +{
> + unsigned int bitflips = 0;
> + u8 status;
> +
> + pr_debug("%s\n", __func__);
> +
> + /* Check Read Status */
> + chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
> + status = chip->read_byte(mtd);
> +
> + /* timeout */
> + if (!(status & NAND_STATUS_READY)) {
> + pr_info("BENAND : Time Out!\n");
> + return -EIO;
> + }
> +
> + /* uncorrectable */
> + else if (status & NAND_STATUS_FAIL) {
> + pr_info("BENAND : Uncorrectable!\n");
> + mtd->ecc_stats.failed++;
> + }
> +
> + /* correctable */
> + else if (status & NAND_STATUS_RECOM_REWRT) {
> + pr_info("BENAND : Recommended to rewrite!\n");
> + bitflips = chip->ecc.strength;

In your case this might be okay, as you set strength to 1.
Otherweise you'd have to report the real number of bitflips.

--
Thanks,
//richard


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