Re: [PATCH v3 03/40] mtd: rawnand: Create a new enumeration to describe OOB placement

[Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>]

On Thu, 19 Sep 2019 21:31:03 +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 in-bad/out-of-band

						   ^in-band

> layout which is only described for hardware engines (OOB first,
> syndrome).

It's not really about in-band/out-of-band data placement (though it
also has an impact on it since free OOB bytes are sometimes protected
by ECC or placed next to it), more ECC bytes placement.

> 
> Create a new enumeration to describe this placement.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> ---
>  drivers/mtd/nand/raw/nand_base.c |  5 +++++
>  include/linux/mtd/rawnand.h      | 12 ++++++++++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index e6c483ec191a..74e9289e931c 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -4842,6 +4842,11 @@ static const char * const nand_ecc_modes[] = {
>  	[NAND_ECC_ON_DIE]	= "on-die",
>  };
>  
> +static const char * const nand_ecc_engine_oob_placement[] = {

			     ^nand_ecc_placement ?

> +	[NAND_ECC_SYNDROME_OOB_PLACEMENT] = "hw_syndrome",
> +	[NAND_ECC_OOB_FIRST_PLACEMENT] = "hw_oob_first",

Since this is something you introduce, I'd recommend to change the
naming here:

s/NAND_ECC_SYNDROME_OOB_PLACEMENT/NAND_ECC_PLACEMENT_INTERLEAVED/
s/hw_syndrome/ecc-interleaved/
s/NAND_ECC_OOB_FIRST_PLACEMENT/NAND_ECC_PLACEMENT_FIRST/
s/hw_oob_first/ecc-first/

> +};
> +
>  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 ccdc0c314acc..89f964816f2c 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -93,6 +93,18 @@ enum nand_ecc_mode {
>  	NAND_ECC_ON_DIE,
>  };
>  
> +/**
> + * enum nand_ecc_engine_oob_placement - NAND ECC engine OOB placement
> + * @NAND_ECC_DEFAULT_OOB_PLACEMENT: Standard layout, or not specified

Maybe describe what the standard layout is (ECC placed at the end), and
mention that "not specified/default" means the driver can decide to put
the ECC/free-OOB bytes where he wants.

> + * @NAND_ECC_SYNDROME_OOB_PLACEMENT: Syndrome layout (interlaced)
> + * @NAND_ECC_OOB_FIRST_PLACEMENT: Free OOB bytes first
> + */
> +enum nand_ecc_engine_oob_placement {
> +	NAND_ECC_DEFAULT_OOB_PLACEMENT,
> +	NAND_ECC_SYNDROME_OOB_PLACEMENT,
> +	NAND_ECC_OOB_FIRST_PLACEMENT,
> +};
> +
>  enum nand_ecc_algo {
>  	NAND_ECC_UNKNOWN,
>  	NAND_ECC_HAMMING,


______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/