Re: [RESEND v5 07/21] mtd: rawnand: Create a new enumeration to describe OOB placement

[Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>]

On Tue, 26 May 2020 21:56:19 +0200
Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:

> There is currently a confusion between the ECC type/mode/provider
> (eg. hardware, software, on-die or none) and the ECC bytes placement.
> 
> Create a new enumeration to describe this placement.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> ---
>  drivers/mtd/nand/raw/nand_base.c |  4 ++++
>  include/linux/mtd/rawnand.h      | 12 ++++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index ef70ca0828c3..a4470a19c805 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -5018,6 +5018,10 @@ static const char * const nand_ecc_modes[] = {
>  	[NAND_ECC_ON_DIE]	= "on-die",
>  };
>  
> +static const char * const nand_ecc_placement[] = {
> +	[NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved",
> +};
> +
>  static int of_get_nand_ecc_mode(struct device_node *np)
>  {
>  	const char *pm;
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 8187056dd3a0..6eb4d91b07eb 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -92,6 +92,18 @@ enum nand_ecc_mode {
>  	NAND_ECC_ON_DIE,
>  };
>  
> +/**
> + * enum nand_ecc_placement - NAND ECC placement
> + * @NAND_ECC_PLACEMENT_FREE: The driver can decide where to put ECC bytes.

Can we name that one UNDEFINED instead of FREE, and it's not really the
driver that decides (unless you have a choice or use SW ECC), more the ECC
engine itself.

> + *                           Default behavior is to put them at the end of the
> + *                           OOB area.

I wouldn't even define a default behavior here, but instead add a value for
OOB/TAIL placement.

> + * @NAND_ECC_PLACEMENT_INTERLEAVED: Syndrome layout: interleave data and OOB.


									     ^ECC bytes

> + */
> +enum nand_ecc_placement {
> +	NAND_ECC_PLACEMENT_FREE,
> +	NAND_ECC_PLACEMENT_INTERLEAVED,
> +};
> +
>  enum nand_ecc_algo {
>  	NAND_ECC_UNKNOWN,
>  	NAND_ECC_HAMMING,


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