Re: [PATCH 1/3] mtd: nand: add support for "nand-ecc-algo" DT property

Boris Brezillon
2016-04-25T10:11:59Z

On Fri, 22 Apr 2016 13:23:13 +0200
Rafał Miłecki <zajec5@gmail.com> wrote:

> So far it was only possible to specify ECC algorithm using "soft" and
> "soft_bch" values of nand-ecc-mode prop. There wasn't a way to specify
> it for a hardware ECC mode.
>
> Now that we have independent field in NAND subsystem for storing info
> about ECC algorithm we may also add support for this new DT property.
>
> Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
> ---
> Documentation/devicetree/bindings/mtd/nand.txt | 2 ++
> drivers/mtd/nand/nand_base.c | 20 +++++++++++++-------
> 2 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/nand.txt b/Documentation/devicetree/bindings/mtd/nand.txt
> index a17662b..5ac4ab7 100644
> --- a/Documentation/devicetree/bindings/mtd/nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/nand.txt
> @@ -22,6 +22,8 @@ Optional NAND chip properties:
> - nand-ecc-mode : String, operation mode of the NAND ecc mode.
> Supported values are: "none", "soft", "hw", "hw_syndrome", "hw_oob_first",
> "soft_bch".
> +- nand-ecc-algo: string, algorithm of NAND ECC.
> + Supported values are: "hamming", "bch".

Rob, any objection to this binding change (and the one in patch 3).
Please note that everything is backward compatible.

Thanks,

Boris

> - nand-bus-width : 8 or 16 bus width if not present 8
> - nand-on-flash-bbt: boolean to enable on flash bbt option if not present false
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 7bc37b4..a5417a0 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -4003,17 +4003,23 @@ static int of_get_nand_ecc_mode(struct device_node *np)
> return -ENODEV;
> }
>
> +static const char * const nand_ecc_algos[] = {
> + [NAND_ECC_HAMMING] = "hamming",
> + [NAND_ECC_BCH] = "bch",
> +};
> +
> static int of_get_nand_ecc_algo(struct device_node *np)
> {
> const char *pm;
> - int err;
> + int err, i;
>
> - /*
> - * TODO: Read ECC algo OF property and map it to enum nand_ecc_algo.
> - * It's not implemented yet as currently NAND subsystem ignores
> - * algorithm explicitly set this way. Once it's handled we should
> - * document & support new property.
> - */
> + err = of_property_read_string(np, "nand-ecc-algo", &pm);
> + if (!err) {
> + for (i = 0; i < ARRAY_SIZE(nand_ecc_algos); i++)
> + if (!strcasecmp(pm, nand_ecc_algos[i]))
> + return i;
> + return -ENODEV;
> + }
>
> /*
> * For backward compatibility we also read "nand-ecc-mode" checking

--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering