Re: [PATCH v6 14/18] mtd: nand: Add more parameters to the nand_ecc_props structure

[Miquel Raynal <miquel.raynal@bootlin.com>]

Boris Brezillon <boris.brezillon@collabora.com> wrote on Thu, 28 May
2020 16:34:24 +0200:

> On Thu, 28 May 2020 13:31:09 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > Prepare the migration to the generic ECC framework by adding more
> > fields to the nand_ecc_props structure which will be used widely to
> > describe different kind of ECC properties.
> > 
> > Doing this imposes to move the engine type, ECC placement and
> > algorithm enumerations in a shared place: nand.h.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  include/linux/mtd/nand.h    | 52 +++++++++++++++++++++++++++++++++++++
> >  include/linux/mtd/rawnand.h | 44 -------------------------------
> >  2 files changed, 52 insertions(+), 44 deletions(-)
> > 
> > diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
> > index 6add464fd18b..2e9af24936cd 100644
> > --- a/include/linux/mtd/nand.h
> > +++ b/include/linux/mtd/nand.h
> > @@ -127,14 +127,66 @@ struct nand_page_io_req {
> >  	int mode;
> >  };
> >  
> > +/**
> > + * enum nand_ecc_engine_type - NAND ECC engine type
> > + * @NAND_ECC_ENGINE_TYPE_INVALID: Invalid value
> > + * @NAND_ECC_ENGINE_TYPE_NONE: No ECC correction
> > + * @NAND_ECC_ENGINE_TYPE_SOFT: Software ECC correction
> > + * @NAND_ECC_ENGINE_TYPE_ON_HOST: On host hardware ECC correction
> > + * @NAND_ECC_ENGINE_TYPE_ON_DIE: On chip hardware ECC correction
> > + */
> > +enum nand_ecc_engine_type {
> > +	NAND_ECC_ENGINE_TYPE_INVALID,
> > +	NAND_ECC_ENGINE_TYPE_NONE,
> > +	NAND_ECC_ENGINE_TYPE_SOFT,
> > +	NAND_ECC_ENGINE_TYPE_ON_HOST,
> > +	NAND_ECC_ENGINE_TYPE_ON_DIE,
> > +};
> > +
> > +/**
> > + * enum nand_ecc_placement - NAND ECC bytes placement
> > + * @NAND_ECC_PLACEMENT_UNKNOWN: The actual position of the ECC bytes is unknown
> > + * @NAND_ECC_PLACEMENT_OOB: The ECC bytes are located in the OOB area
> > + * @NAND_ECC_PLACEMENT_INTERLEAVED: Syndrome layout, there are ECC bytes
> > + *                                  interleaved with regular data in the main
> > + *                                  area
> > + */
> > +enum nand_ecc_placement {
> > +	NAND_ECC_PLACEMENT_UNKNOWN,
> > +	NAND_ECC_PLACEMENT_OOB,
> > +	NAND_ECC_PLACEMENT_INTERLEAVED,
> > +};
> > +
> > +/**
> > + * enum nand_ecc_algo - NAND ECC algorithm
> > + * @NAND_ECC_ALGO_UNKNOWN: Unknown algorithm
> > + * @NAND_ECC_ALGO_HAMMING: Hamming algorithm
> > + * @NAND_ECC_ALGO_BCH: Bose-Chaudhuri-Hocquenghem algorithm
> > + * @NAND_ECC_ALGO_RS: Reed-Solomon algorithm
> > + */
> > +enum nand_ecc_algo {
> > +	NAND_ECC_ALGO_UNKNOWN,
> > +	NAND_ECC_ALGO_HAMMING,
> > +	NAND_ECC_ALGO_BCH,
> > +	NAND_ECC_ALGO_RS,
> > +};
> > +
> >  /**
> >   * struct nand_ecc_props - NAND ECC properties
> > + * @engine_type: ECC engine type
> > + * @placement: OOB placement (if relevant)
> > + * @algo: ECC algorithm (if relevant)
> >   * @strength: ECC strength
> >   * @step_size: Number of bytes per step
> > + * @flags: Misc properties  
> 
> I'd like to hear more about that one. What is this about? I'd rather
> not add a field if it's not needed.
> 

It is used in patch 18/18 to store the NAND_ECC_MAXIMIZE flag. And I
expect others to come later...