[U-Boot] [PATCH v3 5/5] mtd: nand: mxs_nand: add minimal ECC support

[Stefan Agner <stefan@agner.ch>]

Hi Stefano,

On 30.04.2018 10:08, Stefan Agner wrote:
> On 27.04.2018 09:31, Stefano Babic wrote:
>> Hi Stefan,
>>
>> On 11/04/2018 18:04, Stefan Agner wrote:
>>> From: Stefan Agner <stefan.agner@toradex.com>
>>>
>>> Add support for minimum ECC strength supported by the NAND chip.
>>> This aligns with the behavior when using the fsl,use-minimum-ecc
>>> device tree property in Linux.
>>>
>>> Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
>>> ---
>>>
>>> Changes in v3: None
>>> Changes in v2: None
>>>
>>>  drivers/mtd/nand/Kconfig    |  8 +++++
>>>  drivers/mtd/nand/mxs_nand.c | 71 +++++++++++++++++++++++++++++--------
>>>  2 files changed, 65 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
>>> index 4db259fcb2..c039b9cc60 100644
>>> --- a/drivers/mtd/nand/Kconfig
>>> +++ b/drivers/mtd/nand/Kconfig
>>> @@ -152,6 +152,14 @@ config NAND_MXS
>>>  	  This enables NAND driver for the NAND flash controller on the
>>>  	  MXS processors.
>>>
>>> +if NAND_MXS
>>> +
>>> +config NAND_MXS_USE_MINIMUM_ECC
>>> +	bool "Use minimum ECC strength supported by the controller"
>>> +	default false
>>> +
>>> +endif
>>> +
>>>  config NAND_ZYNQ
>>>  	bool "Support for Zynq Nand controller"
>>>  	select SYS_NAND_SELF_INIT
>>> diff --git a/drivers/mtd/nand/mxs_nand.c b/drivers/mtd/nand/mxs_nand.c
>>> index 2696b543ef..8305bf2302 100644
>>> --- a/drivers/mtd/nand/mxs_nand.c
>>> +++ b/drivers/mtd/nand/mxs_nand.c
>>> @@ -211,11 +211,52 @@ static inline int mxs_nand_calc_mark_offset(struct bch_geometry *geo,
>>>  	return 0;
>>>  }
>>>
>>> +static inline unsigned int mxs_nand_max_ecc_strength_supported(void)
>>> +{
>>> +	/* Refer to Chapter 17 for i.MX6DQ, Chapter 18 for i.MX6SX */
>>> +	if (is_mx6sx() || is_mx7())
>>> +		return 62;
>>> +	else
>>> +		return 40;
>>> +}
>>> +
>>> +static inline int mxs_nand_calc_ecc_layout_by_info(struct bch_geometry *geo,
>>> +						   struct mtd_info *mtd)
>>> +{
>>> +	struct nand_chip *chip = mtd_to_nand(mtd);
>>> +
>>> +	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
>>> +		return -ENOTSUPP;
>>> +
>>> +	switch (chip->ecc_step_ds) {
>>> +	case SZ_512:
>>> +		geo->gf_len = 13;
>>> +		break;
>>> +	case SZ_1K:
>>> +		geo->gf_len = 14;
>>> +		break;
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	geo->ecc_chunk_size = chip->ecc_step_ds;
>>> +	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
>>> +
>>> +	/* Keep the C >= O */
>>> +	if (geo->ecc_chunk_size < mtd->oobsize)
>>> +		return -EINVAL;
>>> +
>>> +	if (geo->ecc_strength > mxs_nand_max_ecc_strength_supported())
>>> +		return -EINVAL;
>>> +
>>> +	geo->ecc_chunk_count = mtd->writesize / geo->ecc_chunk_size;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>  static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
>>>  					   struct mtd_info *mtd)
>>>  {
>>> -	unsigned int max_ecc_strength_supported;
>>> -
>>>  	/* The default for the length of Galois Field. */
>>>  	geo->gf_len = 13;
>>>
>>> @@ -235,12 +276,6 @@ static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
>>>
>>>  	geo->ecc_chunk_count = mtd->writesize / geo->ecc_chunk_size;
>>>
>>> -	/* Refer to Chapter 17 for i.MX6DQ, Chapter 18 for i.MX6SX */
>>> -	if (is_mx6sx() || is_mx7())
>>> -		max_ecc_strength_supported = 62;
>>> -	else
>>> -		max_ecc_strength_supported = 40;
>>> -
>>>  	/*
>>>  	 * Determine the ECC layout with the formula:
>>>  	 *	ECC bits per chunk = (total page spare data bits) /
>>> @@ -252,10 +287,8 @@ static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
>>>  	geo->ecc_strength = ((mtd->oobsize - MXS_NAND_METADATA_SIZE) * 8)
>>>  			/ (geo->gf_len * geo->ecc_chunk_count);
>>>
>>> -	geo->ecc_strength = min(round_down(geo->ecc_strength, 2), max_ecc_strength_supported);
>>> -
>>> -	if (mxs_nand_calc_mark_offset(geo, mtd->writesize) < 0)
>>> -		return -EINVAL;
>>> +	geo->ecc_strength = min(round_down(geo->ecc_strength, 2),
>>> +				mxs_nand_max_ecc_strength_supported());
>>>
>>>  	return 0;
>>>  }
>>> @@ -1006,9 +1039,19 @@ static int mxs_nand_setup_ecc(struct mtd_info *mtd)
>>>  	struct bch_geometry *geo = &nand_info->bch_geometry;
>>>  	struct mxs_bch_regs *bch_regs = (struct mxs_bch_regs *)MXS_BCH_BASE;
>>>  	uint32_t tmp;
>>> +	int ret = -ENOTSUPP;
>>>
>>> -	if (mxs_nand_calc_ecc_layout(geo, mtd))
>>> -		return -EINVAL;
>>> +#ifdef CONFIG_NAND_MXS_USE_MINIMUM_ECC
>>> +	ret = mxs_nand_calc_ecc_layout_by_info(geo, mtd);
>>> +#endif
>>> +
>>> +	if (ret == -ENOTSUPP)
>>> +		ret = mxs_nand_calc_ecc_layout(geo, mtd);
>>> +
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	mxs_nand_calc_mark_offset(geo, mtd->writesize);
>>>
>>>  	/* Configure BCH and set NFC geometry */
>>>  	mxs_reset_block(&bch_regs->hw_bch_ctrl_reg);
>>>
>>
>> This is not completely clear to me - is this series replaced by :
>>
>> 	http://patchwork.ozlabs.org/patch/902010/
> 
> No, the other patch set is on-top of this work.
> 
> With this patch set I already introduce minimum ECC, but by just using a
> config symbol. The other patchset allows to enable the same using the
> device tree property.
> 
> I guess the config symbol is still useful for non-dt platforms or SPLs.

Is there anything stopping these two patchset from getting merged?

--
Stefan