Re: [PATCH v3 37/40] mtd: spinand: Propagate ECC information to the MTD structure

[Emil Lenngren <emil.lenngren@xxxxxxxxx>]

Hi,

Den tors 19 sep. 2019 kl 21:56 skrev Miquel Raynal <miquel.raynal@xxxxxxxxxxx>:
>
> This is done by default in the raw NAND core (nand_base.c) but was
> missing in the SPI-NAND core. Without these two lines the ecc_strength
> and ecc_step_size values are not exported to the user through sysfs.
>
> This fix depends on recent changes and should not be backported as-is.
>
> Fixes: 7529df465248 ("mtd: nand: Add core infrastructure to support SPI NANDs")
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> ---
>  drivers/mtd/nand/spi/core.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index a521eeb0d351..36b99f68da81 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1135,6 +1135,10 @@ static int spinand_init(struct spinand_device *spinand)
>
>         mtd->oobavail = ret;
>
> +       /* Propagate ECC information to mtd_info */
> +       mtd->ecc_strength = nand->ecc.ctx.conf.strength;
> +       mtd->ecc_step_size = nand->ecc.ctx.conf.step_size;
> +
>         return 0;
>
>  err_cleanup_ecc_engine:
> --

If I follow the code flow correctly, it seems this is more important
than just exposing the value to the user through sysfs. The
mtd_read_oob function uses the ecc_strength and bitflip_threshold
values to decide if it should return -EUCLEAN or 0 for a read with
correctable bitflips:

if (mtd->ecc_strength == 0)
        return 0; /* device lacks ecc */
return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;

The -EUCLEAN error code is then used in UBI for the wear level logic,
so it would be nice if this could be fixed.
Now both ecc_strength and bitflip_threshold is 0 for me with my SPI
NAND flash, as exposed through sysfs, so I assume the wear level logic
doesn't work right now.

/Emil

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