Hi,
We are also having the same problem where the IFC (nand flash) was
reporting ECC uncorrectable errors on single bitflips with erased pages.
Applying this patch with some minor modifications seems to solve our
issue. We are still doing more testing but recent results looks promising.
Our kernel is 4.4.6 so we have to modify it a bit to fit the old ECC
layout structure. We just have a few comments about the patch:
> - if (!is_blank(mtd, bufnum))
> - ctrl->nand_stat |=
> - IFC_NAND_EVTER_STAT_ECCER;
> - break;
> + ctrl->nand_stat |= IFC_NAND_EVTER_STAT_ECCER;
Added 'error = 0' after setting the flag since no error was actually
corrected.
> - if (ctrl->nand_stat & IFC_NAND_EVTER_STAT_ECCER)
> - dev_err(priv->dev, "NAND Flash ECC Uncorrectable Error\n");
> -
> if (ctrl->nand_stat != IFC_NAND_EVTER_STAT_OPC)
> mtd->ecc_stats.failed++;
> +
> + if (ctrl->nand_stat & IFC_NAND_EVTER_STAT_ECCER) {
> + int res;
> +
> + if (!oob_required)
> + fsl_ifc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
> +
> + res = check_erased_page(chip, buf);
> + return res;
> + }
We have to do the check IFC_NAND_EVTER_STAT_ECCER first because the
condition (ctrl->nand_stat != IFC_NAND_EVTER_STAT_OPC) will never be
true since IFC always sets IFC_NAND_EVTER_STAT_ECCER on empty pages.
Incrementing failed stats first before doing check_erased_page() makes
nand_read() report ECC error all time.
Our exact modification was:
if (ctrl->nand_stat & IFC_NAND_EVTER_STAT_ECCER) {
if (!oob_required)
fsl_ifc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
return check_erased_page(chip, buf);
}
if (ctrl->nand_stat != IFC_NAND_EVTER_STAT_OPC)
mtd->ecc_stats.failed++;
Because check_erased_page() will be updating the failed stat anyway.
Cheers,
Darwin
