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Date:   Wed, 4 Jan 2017 15:59:15 +0100
From:   Marek Vasut <marek.vasut@...il.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Richard Weinberger <richard@....at>,
        linux-mtd@...ts.infradead.org
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        Icenowy Zheng <icenowy@...c.xyz>, Valdis.Kletnieks@...edu,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/15] mtd: nand: get rid of busw parameter

On 01/03/2017 02:01 PM, Boris Brezillon wrote:
> Auto-detection functions are passed a busw parameter to retrieve the actual
> NAND bus width and eventually set the correct value in chip->options.
> Rework the nand_get_flash_type() function to get rid of this extra
> parameter and let detection code directly set the NAND_BUSWIDTH_16 flag in
> chip->options if needed.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

Reviewed-by: Marek Vasut <marek.vasut@...il.com>

> ---
>  drivers/mtd/nand/nand_base.c | 68 ++++++++++++++++++++++++--------------------
>  1 file changed, 37 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 309f2e113d39..3a31b705af6f 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3348,8 +3348,10 @@ static void nand_shutdown(struct mtd_info *mtd)
>  }
>  
>  /* Set default functions */
> -static void nand_set_defaults(struct nand_chip *chip, int busw)
> +static void nand_set_defaults(struct nand_chip *chip)
>  {
> +	unsigned int busw = chip->options & NAND_BUSWIDTH_16;
> +
>  	/* check for proper chip_delay setup, set 20us if not */
>  	if (!chip->chip_delay)
>  		chip->chip_delay = 20;
> @@ -3525,7 +3527,7 @@ static void nand_onfi_detect_micron(struct nand_chip *chip,
>  /*
>   * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
>   */
> -static int nand_flash_detect_onfi(struct nand_chip *chip, int *busw)
> +static int nand_flash_detect_onfi(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	struct nand_onfi_params *p = &chip->onfi_params;
> @@ -3594,9 +3596,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip, int *busw)
>  	chip->bits_per_cell = p->bits_per_cell;
>  
>  	if (onfi_feature(chip) & ONFI_FEATURE_16_BIT_BUS)
> -		*busw = NAND_BUSWIDTH_16;
> -	else
> -		*busw = 0;
> +		chip->options |= NAND_BUSWIDTH_16;
>  
>  	if (p->ecc_bits != 0xff) {
>  		chip->ecc_strength_ds = p->ecc_bits;
> @@ -3629,7 +3629,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip, int *busw)
>  /*
>   * Check if the NAND chip is JEDEC compliant, returns 1 if it is, 0 otherwise.
>   */
> -static int nand_flash_detect_jedec(struct nand_chip *chip, int *busw)
> +static int nand_flash_detect_jedec(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	struct nand_jedec_params *p = &chip->jedec_params;
> @@ -3690,9 +3690,7 @@ static int nand_flash_detect_jedec(struct nand_chip *chip, int *busw)
>  	chip->bits_per_cell = p->bits_per_cell;
>  
>  	if (jedec_feature(chip) & JEDEC_FEATURE_16_BIT_BUS)
> -		*busw = NAND_BUSWIDTH_16;
> -	else
> -		*busw = 0;
> +		chip->options |= NAND_BUSWIDTH_16;
>  
>  	/* ECC info */
>  	ecc = &p->ecc_info[0];
> @@ -3781,7 +3779,7 @@ static int nand_get_bits_per_cell(u8 cellinfo)
>   * chip. The rest of the parameters must be decoded according to generic or
>   * manufacturer-specific "extended ID" decoding patterns.
>   */
> -static void nand_decode_ext_id(struct nand_chip *chip, int *busw)
> +static void nand_decode_ext_id(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	int extid, id_len = chip->id.len;
> @@ -3834,7 +3832,6 @@ static void nand_decode_ext_id(struct nand_chip *chip, int *busw)
>  		/* Calc blocksize */
>  		mtd->erasesize = (128 * 1024) <<
>  			(((extid >> 1) & 0x04) | (extid & 0x03));
> -		*busw = 0;
>  	} else if (id_len == 6 && id_data[0] == NAND_MFR_HYNIX &&
>  			!nand_is_slc(chip)) {
>  		unsigned int tmp;
> @@ -3875,7 +3872,6 @@ static void nand_decode_ext_id(struct nand_chip *chip, int *busw)
>  			mtd->erasesize = 768 * 1024;
>  		else
>  			mtd->erasesize = (64 * 1024) << tmp;
> -		*busw = 0;
>  	} else {
>  		/* Calc pagesize */
>  		mtd->writesize = 1024 << (extid & 0x03);
> @@ -3888,7 +3884,8 @@ static void nand_decode_ext_id(struct nand_chip *chip, int *busw)
>  		mtd->erasesize = (64 * 1024) << (extid & 0x03);
>  		extid >>= 2;
>  		/* Get buswidth information */
> -		*busw = (extid & 0x01) ? NAND_BUSWIDTH_16 : 0;
> +		if (extid & 0x1)
> +			chip->options |= NAND_BUSWIDTH_16;
>  
>  		/*
>  		 * Toshiba 24nm raw SLC (i.e., not BENAND) have 32B OOB per
> @@ -3913,8 +3910,7 @@ static void nand_decode_ext_id(struct nand_chip *chip, int *busw)
>   * decodes a matching ID table entry and assigns the MTD size parameters for
>   * the chip.
>   */
> -static void nand_decode_id(struct nand_chip *chip, struct nand_flash_dev *type,
> -			   int *busw)
> +static void nand_decode_id(struct nand_chip *chip, struct nand_flash_dev *type)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	u8 *id_data = chip->id.data;
> @@ -3923,7 +3919,6 @@ static void nand_decode_id(struct nand_chip *chip, struct nand_flash_dev *type,
>  	mtd->erasesize = type->erasesize;
>  	mtd->writesize = type->pagesize;
>  	mtd->oobsize = mtd->writesize / 32;
> -	*busw = type->options & NAND_BUSWIDTH_16;
>  
>  	/* All legacy ID NAND are small-page, SLC */
>  	chip->bits_per_cell = 1;
> @@ -3986,7 +3981,7 @@ static inline bool is_full_id_nand(struct nand_flash_dev *type)
>  }
>  
>  static bool find_full_id_nand(struct nand_chip *chip,
> -			      struct nand_flash_dev *type, int *busw)
> +			      struct nand_flash_dev *type)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	u8 *id_data = chip->id.data;
> @@ -4004,8 +3999,6 @@ static bool find_full_id_nand(struct nand_chip *chip,
>  		chip->onfi_timing_mode_default =
>  					type->onfi_timing_mode_default;
>  
> -		*busw = type->options & NAND_BUSWIDTH_16;
> -
>  		if (!mtd->name)
>  			mtd->name = type->name;
>  
> @@ -4066,9 +4059,24 @@ static int nand_get_flash_type(struct nand_chip *chip,
>  	if (!type)
>  		type = nand_flash_ids;
>  
> +	/*
> +	 * Save the NAND_BUSWIDTH_16 flag before letting auto-detection logic
> +	 * override it.
> +	 * This is required to make sure initial NAND bus width set by the
> +	 * NAND controller driver is coherent with the real NAND bus width
> +	 * (extracted by auto-detection code).
> +	 */
> +	busw = chip->options & NAND_BUSWIDTH_16;
> +
> +	/*
> +	 * The flag is only set (never cleared), reset it to its default value
> +	 * before starting auto-detection.
> +	 */
> +	chip->options &= ~NAND_BUSWIDTH_16;
> +
>  	for (; type->name != NULL; type++) {
>  		if (is_full_id_nand(type)) {
> -			if (find_full_id_nand(chip, type, &busw))
> +			if (find_full_id_nand(chip, type))
>  				goto ident_done;
>  		} else if (dev_id == type->dev_id) {
>  			break;
> @@ -4078,11 +4086,11 @@ static int nand_get_flash_type(struct nand_chip *chip,
>  	chip->onfi_version = 0;
>  	if (!type->name || !type->pagesize) {
>  		/* Check if the chip is ONFI compliant */
> -		if (nand_flash_detect_onfi(chip, &busw))
> +		if (nand_flash_detect_onfi(chip))
>  			goto ident_done;
>  
>  		/* Check if the chip is JEDEC compliant */
> -		if (nand_flash_detect_jedec(chip, &busw))
> +		if (nand_flash_detect_jedec(chip))
>  			goto ident_done;
>  	}
>  
> @@ -4096,9 +4104,9 @@ static int nand_get_flash_type(struct nand_chip *chip,
>  
>  	if (!type->pagesize) {
>  		/* Decode parameters from extended ID */
> -		nand_decode_ext_id(chip, &busw);
> +		nand_decode_ext_id(chip);
>  	} else {
> -		nand_decode_id(chip, type, &busw);
> +		nand_decode_id(chip, type);
>  	}
>  	/* Get chip options */
>  	chip->options |= type->options;
> @@ -4118,9 +4126,8 @@ static int nand_get_flash_type(struct nand_chip *chip,
>  	}
>  
>  	if (chip->options & NAND_BUSWIDTH_AUTO) {
> -		WARN_ON(chip->options & NAND_BUSWIDTH_16);
> -		chip->options |= busw;
> -		nand_set_defaults(chip, busw);
> +		WARN_ON(busw & NAND_BUSWIDTH_16);
> +		nand_set_defaults(chip);
>  	} else if (busw != (chip->options & NAND_BUSWIDTH_16)) {
>  		/*
>  		 * Check, if buswidth is correct. Hardware drivers should set
> @@ -4129,9 +4136,8 @@ static int nand_get_flash_type(struct nand_chip *chip,
>  		pr_info("device found, Manufacturer ID: 0x%02x, Chip ID: 0x%02x\n",
>  			maf_id, dev_id);
>  		pr_info("%s %s\n", nand_manuf_ids[maf_idx].name, mtd->name);
> -		pr_warn("bus width %d instead %d bit\n",
> -			   (chip->options & NAND_BUSWIDTH_16) ? 16 : 8,
> -			   busw ? 16 : 8);
> +		pr_warn("bus width %d instead of %d bits\n", busw ? 16 : 8,
> +			(chip->options & NAND_BUSWIDTH_16) ? 16 : 8);
>  		return -EINVAL;
>  	}
>  
> @@ -4359,7 +4365,7 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
>  		return -EINVAL;
>  	}
>  	/* Set the default functions */
> -	nand_set_defaults(chip, chip->options & NAND_BUSWIDTH_16);
> +	nand_set_defaults(chip);
>  
>  	/* Read the flash type */
>  	ret = nand_get_flash_type(chip, table);
> 


-- 
Best regards,
Marek Vasut

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