Subject: Re: [PATCH v9 9/9] mtd: rawnand: Move the user input parsing bits to the ECC framework

From: Boris Brezillon <[email-masked]>
Date: Tue, 2 Jun 2020 18:18:58 +0200

On Tue,  2 Jun 2020 16:31:24 +0200
Miquel Raynal <[email-masked]> wrote:

> Many helpers are generic to all NAND chips, they should not be
> restricted to be only used by raw NAND controller drivers. They might
> later be used by generic ECC engines and SPI-NAND devices as well so
> move them into a more generic place.
> 
> To avoid moving all the raw NAND core "history" into the generic NAND
> layer, we already moved certain bits into legacy helpers in the raw
> NAND core to ensure backward compatibility.
> 
> Signed-off-by: Miquel Raynal <[email-masked]>
> ---
>  drivers/mtd/nand/ecc.c                       | 138 +++++++++++++++++
>  drivers/mtd/nand/raw/atmel/nand-controller.c |   3 +-
>  drivers/mtd/nand/raw/denali.c                |   3 +
>  drivers/mtd/nand/raw/nand_base.c             | 150 ++-----------------
>  drivers/mtd/nand/raw/sunxi_nand.c            |   3 +-
>  drivers/mtd/nand/raw/tegra_nand.c            |   5 +-
>  include/linux/mtd/nand.h                     |   7 +
>  include/linux/mtd/rawnand.h                  |   1 -
>  8 files changed, 166 insertions(+), 144 deletions(-)
> 
> diff --git a/drivers/mtd/nand/ecc.c b/drivers/mtd/nand/ecc.c
> index ad08a047dfc5..1ac7aaa6c6c2 100644
> --- a/drivers/mtd/nand/ecc.c
> +++ b/drivers/mtd/nand/ecc.c
> @@ -328,6 +328,144 @@ const struct mtd_ooblayout_ops *nand_get_large_page_hamming_ooblayout(void)
>  }
>  EXPORT_SYMBOL_GPL(nand_get_large_page_hamming_ooblayout);
>  
> +static enum nand_ecc_engine_type
> +of_get_nand_ecc_engine_type(struct device_node *np)
> +{
> +	return NAND_ECC_ENGINE_TYPE_INVALID;
> +}
> +
> +static const char * const nand_ecc_placement[] = {
> +	[NAND_ECC_PLACEMENT_OOB] = "oob",
> +	[NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved",
> +};
> +
> +enum nand_ecc_placement of_get_nand_ecc_placement(struct device_node *np)
> +{
> +	enum nand_ecc_placement placement;
> +	const char *pm;
> +	int err;
> +
> +	err = of_property_read_string(np, "nand-ecc-placement", &pm);
> +	if (!err) {
> +		for (placement = NAND_ECC_PLACEMENT_OOB;
> +		     placement < ARRAY_SIZE(nand_ecc_placement); placement++) {
> +			if (!strcasecmp(pm, nand_ecc_placement[placement]))
> +				return placement;
> +		}
> +	}
> +
> +	return NAND_ECC_PLACEMENT_UNKNOWN;
> +}
> +
> +static const char * const nand_ecc_algos[] = {
> +	[NAND_ECC_ALGO_HAMMING]	= "hamming",
> +	[NAND_ECC_ALGO_BCH]	= "bch",
> +	[NAND_ECC_ALGO_RS]	= "rs",

Can we use spaces instead of tabs, as done for nand_ecc_placement?

> +};
> +
> +static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np)
> +{
> +	enum nand_ecc_algo ecc_algo;
> +	const char *pm;
> +	int err;
> +
> +	err = of_property_read_string(np, "nand-ecc-algo", &pm);
> +	if (!err) {
> +		for (ecc_algo = NAND_ECC_ALGO_HAMMING;
> +		     ecc_algo < ARRAY_SIZE(nand_ecc_algos);
> +		     ecc_algo++) {
> +			if (!strcasecmp(pm, nand_ecc_algos[ecc_algo]))
> +				return ecc_algo;
> +		}
> +	}
> +
> +	return NAND_ECC_ALGO_UNKNOWN;
> +}
> +
> +static int of_get_nand_ecc_step_size(struct device_node *np)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = of_property_read_u32(np, "nand-ecc-step-size", &val);
> +	return ret ? ret : val;
> +}
> +
> +static int of_get_nand_ecc_strength(struct device_node *np)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = of_property_read_u32(np, "nand-ecc-strength", &val);
> +	return ret ? ret : val;
> +}
> +
> +static inline bool of_get_nand_ecc_maximize(struct device_node *np)
> +{
> +	return of_property_read_bool(np, "nand-ecc-maximize");
> +}
> +
> +void nand_ecc_read_user_conf(struct nand_device *nand)
> +{
> +	struct device_node *dn = nanddev_get_of_node(nand);
> +	int strength, size;
> +
> +	nand->ecc.user_conf.engine_type = of_get_nand_ecc_engine_type(dn);
> +	nand->ecc.user_conf.algo = of_get_nand_ecc_algo(dn);
> +	nand->ecc.user_conf.placement = of_get_nand_ecc_placement(dn);
> +
> +	strength = of_get_nand_ecc_strength(dn);
> +	if (strength >= 0)
> +		nand->ecc.user_conf.strength = strength;
> +
> +	size = of_get_nand_ecc_step_size(dn);
> +	if (size >= 0)
> +		nand->ecc.user_conf.step_size = size;
> +
> +	if (of_get_nand_ecc_maximize(dn))
> +		nand->ecc.user_conf.flags |= NAND_ECC_MAXIMIZE;
> +}
> +EXPORT_SYMBOL(nand_ecc_read_user_conf);
> +
> +/**
> + * nand_ecc_correction_is_enough - Check if the chip configuration meets the
> + *                                 datasheet requirements.
> + *
> + * @nand: Device to check
> + *
> + * If our configuration corrects A bits per B bytes and the minimum
> + * required correction level is X bits per Y bytes, then we must ensure
> + * both of the following are true:
> + *
> + * (1) A / B >= X / Y
> + * (2) A >= X
> + *
> + * Requirement (1) ensures we can correct for the required bitflip density.
> + * Requirement (2) ensures we can correct even when all bitflips are clumped
> + * in the same sector.
> + */
> +bool nand_ecc_correction_is_enough(struct nand_device *nand)

nand_ecc_is_strong_enough() ?

> +{
> +	const struct nand_ecc_props *reqs = nanddev_get_ecc_requirements(nand);
> +	const struct nand_ecc_props *conf = nanddev_get_ecc_conf(nand);
> +	struct mtd_info *mtd = nanddev_to_mtd(nand);
> +	int corr, ds_corr;
> +
> +	if (conf->step_size == 0 || reqs->step_size == 0)
> +		/* Not enough information */
> +		return true;
> +
> +	/*
> +	 * We get the number of corrected bits per page to compare
> +	 * the correction density.
> +	 */
> +	corr = (mtd->writesize * conf->strength) / conf->step_size;
> +	ds_corr = (mtd->writesize * reqs->strength) / reqs->step_size;
> +
> +	return corr >= ds_corr && conf->strength >= reqs->strength;
> +}
> +EXPORT_SYMBOL(nand_ecc_correction_is_enough);
> +
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Miquel Raynal <[email-masked]>");
>  MODULE_DESCRIPTION("Generic ECC engine");
> diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
> index 08df7f23b859..39d8fe15b8ab 100644
> --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
> +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
> @@ -1046,6 +1046,7 @@ static int atmel_nand_pmecc_init(struct nand_chip *chip)
>  	const struct nand_ecc_props *requirements =
>  		nanddev_get_ecc_requirements(&chip->base);
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct nand_device *nanddev = mtd_to_nanddev(mtd);
>  	struct atmel_nand *nand = to_atmel_nand(chip);
>  	struct atmel_nand_controller *nc;
>  	struct atmel_pmecc_user_req req;
> @@ -1070,7 +1071,7 @@ static int atmel_nand_pmecc_init(struct nand_chip *chip)
>  			chip->ecc.size = val;
>  	}
>  
> -	if (chip->ecc.options & NAND_ECC_MAXIMIZE)
> +	if (nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE)
>  		req.ecc.strength = ATMEL_PMECC_MAXIMIZE_ECC_STRENGTH;

I'd prefer to have that done in 2 steps:

1/ move/duplicate definitions found in rawnand.h
2/ patch rawnand code to finally use the nanddev->ecc.user_conf object
   for the ECC config.

>  	else if (chip->ecc.strength)
>  		req.ecc.strength = chip->ecc.strength;
> diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
> index a6a6464974ec..51bc014ebc0a 100644
> --- a/drivers/mtd/nand/raw/denali.c
> +++ b/drivers/mtd/nand/raw/denali.c
> @@ -1181,6 +1181,7 @@ int denali_chip_init(struct denali_controller *denali,
>  {
>  	struct nand_chip *chip = &dchip->chip;
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct nand_device *nanddev = mtd_to_nanddev(mtd);
>  	struct denali_chip *dchip2;
>  	int i, j, ret;
>  
> @@ -1248,6 +1249,8 @@ int denali_chip_init(struct denali_controller *denali,
>  
>  	mtd_set_ooblayout(mtd, &denali_ooblayout_ops);
>  
> +	nanddev->ecc.user_conf.flags |= NAND_ECC_MAXIMIZE;
> +

Is that correct? I don't find the 

	chip->ecc.options |= NAND_ECC_MAXIMIZE;

removal that this line is replacing.

>  	ret = nand_scan(chip, dchip->nsels);
>  	if (ret)
>  		return ret;
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index afc3506468ba..036e88cb52a1 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -4854,17 +4854,6 @@ static int nand_detect(struct nand_chip *chip, struct nand_flash_dev *type)
>  	return ret;
>  }
>  
> -static const char * const nand_ecc_placement[] = {
> -	[NAND_ECC_PLACEMENT_OOB] = "oob",
> -	[NAND_ECC_PLACEMENT_INTERLEAVED] = "interleaved",
> -};
> -
> -static enum nand_ecc_engine_type
> -of_get_nand_ecc_engine_type(struct device_node *np)
> -{
> -	return NAND_ECC_ENGINE_TYPE_INVALID;
> -}
> -
>  static enum nand_ecc_engine_type
>  of_get_rawnand_ecc_engine_type_legacy(struct device_node *np)
>  {
> @@ -4916,24 +4905,6 @@ of_get_rawnand_ecc_engine_type_legacy(struct device_node *np)
>  	return NAND_ECC_ENGINE_TYPE_INVALID;
>  }
>  
> -enum nand_ecc_placement of_get_nand_ecc_placement(struct device_node *np)
> -{
> -	enum nand_ecc_placement placement;
> -	const char *pm;
> -	int err;
> -
> -	err = of_property_read_string(np, "nand-ecc-placement", &pm);
> -	if (!err) {
> -		for (placement = NAND_ECC_PLACEMENT_OOB;
> -		     placement < ARRAY_SIZE(nand_ecc_placement); placement++) {
> -			if (!strcasecmp(pm, nand_ecc_placement[placement]))
> -				return placement;
> -		}
> -	}
> -
> -	return NAND_ECC_PLACEMENT_UNKNOWN;
> -}
> -
>  enum nand_ecc_placement
>  of_get_rawnand_ecc_placement_legacy(struct device_node *np)
>  {
> @@ -4949,31 +4920,6 @@ of_get_rawnand_ecc_placement_legacy(struct device_node *np)
>  	return NAND_ECC_PLACEMENT_UNKNOWN;
>  }
>  
> -static const char * const nand_ecc_algos[] = {
> -	[NAND_ECC_ALGO_HAMMING]	= "hamming",
> -	[NAND_ECC_ALGO_BCH]	= "bch",
> -	[NAND_ECC_ALGO_RS]	= "rs",
> -};
> -
> -static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np)
> -{
> -	enum nand_ecc_algo ecc_algo;
> -	const char *pm;
> -	int err;
> -
> -	err = of_property_read_string(np, "nand-ecc-algo", &pm);
> -	if (!err) {
> -		for (ecc_algo = NAND_ECC_ALGO_HAMMING;
> -		     ecc_algo < ARRAY_SIZE(nand_ecc_algos);
> -		     ecc_algo++) {
> -			if (!strcasecmp(pm, nand_ecc_algos[ecc_algo]))
> -				return ecc_algo;
> -		}
> -	}
> -
> -	return NAND_ECC_ALGO_UNKNOWN;
> -}
> -
>  static enum nand_ecc_algo of_get_rawnand_ecc_algo_legacy(struct device_node *np)
>  {
>  	const char *pm;
> @@ -4990,48 +4936,10 @@ static enum nand_ecc_algo of_get_rawnand_ecc_algo_legacy(struct device_node *np)
>  	return NAND_ECC_ALGO_UNKNOWN;
>  }
>  
> -static int of_get_nand_ecc_step_size(struct device_node *np)
> -{
> -	int ret;
> -	u32 val;
> -
> -	ret = of_property_read_u32(np, "nand-ecc-step-size", &val);
> -	return ret ? ret : val;
> -}
> -
> -static int of_get_nand_ecc_strength(struct device_node *np)
> -{
> -	int ret;
> -	u32 val;
> -
> -	ret = of_property_read_u32(np, "nand-ecc-strength", &val);
> -	return ret ? ret : val;
> -}
> -
> -static void nand_ecc_read_user_conf(struct nand_chip *chip)
> -{
> -	struct device_node *dn = nand_get_flash_node(chip);
> -	struct nand_device *nand = &chip->base;
> -	int strength, size;
> -
> -	nand->ecc.user_conf.engine_type = of_get_nand_ecc_engine_type(dn);
> -	nand->ecc.user_conf.algo = of_get_nand_ecc_algo(dn);
> -	nand->ecc.user_conf.placement = of_get_nand_ecc_placement(dn);
> -
> -	strength = of_get_nand_ecc_strength(dn);
> -	if (strength >= 0)
> -		nand->ecc.user_conf.strength = strength;
> -
> -	size = of_get_nand_ecc_step_size(dn);
> -	if (size >= 0)
> -		nand->ecc.user_conf.step_size = size;
> -}
> -
>  static void rawnand_ecc_read_legacy_user_conf(struct nand_chip *chip)
>  {
>  	struct device_node *dn = nand_get_flash_node(chip);
> -	struct nand_device *nand = &chip->base;
> -	struct nand_ecc_props *user_conf = &nand->ecc.user_conf;
> +	struct nand_ecc_props *user_conf = &chip->base.ecc.user_conf;
>  
>  	if (user_conf->engine_type != NAND_ECC_ENGINE_TYPE_INVALID)
>  		user_conf->engine_type = of_get_rawnand_ecc_engine_type_legacy(dn);
> @@ -5081,10 +4989,7 @@ static int rawnand_dt_init(struct nand_chip *chip)
>  	if (of_get_nand_on_flash_bbt(dn))
>  		chip->bbt_options |= NAND_BBT_USE_FLASH;
>  
> -	if (of_property_read_bool(dn, "nand-ecc-maximize"))
> -		chip->ecc.options |= NAND_ECC_MAXIMIZE;
> -
> -	nand_ecc_read_user_conf(chip);
> +	nand_ecc_read_user_conf(nand);
>  	rawnand_ecc_read_legacy_user_conf(chip);
>  
>  	/*
> @@ -5214,6 +5119,7 @@ static void nand_scan_ident_cleanup(struct nand_chip *chip)
>  static int nand_set_ecc_soft_ops(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct nand_device *nanddev = mtd_to_nanddev(mtd);
>  	struct nand_ecc_ctrl *ecc = &chip->ecc;
>  
>  	if (WARN_ON(ecc->engine_type != NAND_ECC_ENGINE_TYPE_SOFT))
> @@ -5289,7 +5195,7 @@ static int nand_set_ecc_soft_ops(struct nand_chip *chip)
>  		 * used.
>  		 */
>  		if (mtd->ooblayout == nand_get_large_page_ooblayout() &&
> -		    ecc->options & NAND_ECC_MAXIMIZE) {
> +		    nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE) {
>  			int steps, bytes;
>  
>  			/* Always prefer 1k blocks over 512bytes ones */
> @@ -5529,11 +5435,12 @@ nand_maximize_ecc(struct nand_chip *chip,
>   * @caps: ECC engine caps info structure
>   * @oobavail: OOB size that the ECC engine can use
>   *
> - * Choose the ECC configuration according to following logic
> + * Choose the ECC configuration according to following logic.
>   *
>   * 1. If both ECC step size and ECC strength are already set (usually by DT)
>   *    then check if it is supported by this controller.
> - * 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength.
> + * 2. If the user provided the nand-ecc-maximize property, then select maximum
> + *    ECC strength.
>   * 3. Otherwise, try to match the ECC step size and ECC strength closest
>   *    to the chip's requirement. If available OOB size can't fit the chip
>   *    requirement then fallback to the maximum ECC step size and ECC strength.
> @@ -5544,6 +5451,7 @@ int nand_ecc_choose_conf(struct nand_chip *chip,
>  			 const struct nand_ecc_caps *caps, int oobavail)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct nand_device *nanddev = mtd_to_nanddev(mtd);
>  
>  	if (WARN_ON(oobavail < 0 || oobavail > mtd->oobsize))
>  		return -EINVAL;
> @@ -5551,7 +5459,7 @@ int nand_ecc_choose_conf(struct nand_chip *chip,
>  	if (chip->ecc.size && chip->ecc.strength)
>  		return nand_check_ecc_caps(chip, caps, oobavail);
>  
> -	if (chip->ecc.options & NAND_ECC_MAXIMIZE)
> +	if (nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE)
>  		return nand_maximize_ecc(chip, caps, oobavail);
>  
>  	if (!nand_match_ecc_req(chip, caps, oobavail))
> @@ -5561,43 +5469,6 @@ int nand_ecc_choose_conf(struct nand_chip *chip,
>  }
>  EXPORT_SYMBOL_GPL(nand_ecc_choose_conf);
>  
> -/*
> - * Check if the chip configuration meet the datasheet requirements.
> -
> - * If our configuration corrects A bits per B bytes and the minimum
> - * required correction level is X bits per Y bytes, then we must ensure
> - * both of the following are true:
> - *
> - * (1) A / B >= X / Y
> - * (2) A >= X
> - *
> - * Requirement (1) ensures we can correct for the required bitflip density.
> - * Requirement (2) ensures we can correct even when all bitflips are clumped
> - * in the same sector.
> - */
> -static bool nand_ecc_strength_good(struct nand_chip *chip)
> -{
> -	struct mtd_info *mtd = nand_to_mtd(chip);
> -	struct nand_ecc_ctrl *ecc = &chip->ecc;
> -	const struct nand_ecc_props *requirements =
> -		nanddev_get_ecc_requirements(&chip->base);
> -	int corr, ds_corr;
> -
> -	if (ecc->size == 0 || requirements->step_size == 0)
> -		/* Not enough information */
> -		return true;
> -
> -	/*
> -	 * We get the number of corrected bits per page to compare
> -	 * the correction density.
> -	 */
> -	corr = (mtd->writesize * ecc->strength) / ecc->size;
> -	ds_corr = (mtd->writesize * requirements->strength) /
> -		  requirements->step_size;
> -
> -	return corr >= ds_corr && ecc->strength >= requirements->strength;
> -}
> -
>  static int rawnand_erase(struct nand_device *nand, const struct nand_pos *pos)
>  {
>  	struct nand_chip *chip = container_of(nand, struct nand_chip,
> @@ -5653,6 +5524,7 @@ static const struct nand_ops rawnand_ops = {
>  static int nand_scan_tail(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct nand_device *nanddev = mtd_to_nanddev(mtd);
>  	struct nand_ecc_ctrl *ecc = &chip->ecc;
>  	int ret, i;
>  
> @@ -5880,7 +5752,7 @@ static int nand_scan_tail(struct nand_chip *chip)
>  	mtd->oobavail = ret;
>  
>  	/* ECC sanity check: warn if it's too weak */
> -	if (!nand_ecc_strength_good(chip))
> +	if (!nand_ecc_correction_is_enough(nanddev))

Can we do this rename separately?

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