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Date:   Sun, 23 Aug 2020 15:31:27 +0200
From:   Boris Brezillon <boris.brezillon@collabora.com>
To:     Thirumalesha Narasimhappa <nthirumalesha7@gmail.com>
Cc:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Shivamurthy Shastri <sshivamurthy@micron.com>,
        Chuanhong Guo <gch981213@gmail.com>,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mtd: spinand: micron: add support for MT29F2G01AAAED
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In-Reply-To: <20200823111410.13049-1-nthirumalesha7@gmail.com>
References: <20200823111410.13049-1-nthirumalesha7@gmail.com>
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On Sun, 23 Aug 2020 19:14:10 +0800
Thirumalesha Narasimhappa <nthirumalesha7@gmail.com> wrote:

> The MT29F2G01AAAED is a single die, 2Gb Micron SPI NAND Flash with 4-bit
> ECC
> 
> Signed-off-by: Thirumalesha Narasimhappa <nthirumalesha7@gmail.com>
> ---
>  v2: removed SPINAND_SELECT_TARGET as per the comments & fixed typo errors
> 
>  drivers/mtd/nand/spi/micron.c | 78 +++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/drivers/mtd/nand/spi/micron.c b/drivers/mtd/nand/spi/micron.c
> index 5d370cfcdaaa..c21ca395d657 100644
> --- a/drivers/mtd/nand/spi/micron.c
> +++ b/drivers/mtd/nand/spi/micron.c
> @@ -18,6 +18,9 @@
>  #define MICRON_STATUS_ECC_4TO6_BITFLIPS	(3 << 4)
>  #define MICRON_STATUS_ECC_7TO8_BITFLIPS	(5 << 4)
>  
> +/* For Micron MT29F2G01AAAED Device */
> +#define MICRON_STATUS_ECC_1TO4_BITFLIPS	(1 << 4)
> +

You shouldn't need that new definition (see below).

>  #define MICRON_CFG_CR			BIT(0)
>  
>  /*
> @@ -44,6 +47,19 @@ static SPINAND_OP_VARIANTS(update_cache_variants,
>  		SPINAND_PROG_LOAD_X4(false, 0, NULL, 0),
>  		SPINAND_PROG_LOAD(false, 0, NULL, 0));
>  
> +/* Micron  MT29F2G01AAAED Device */
> +static SPINAND_OP_VARIANTS(read_cache_variants_mt29f2g01aaaed,
> +		SPINAND_PAGE_READ_FROM_CACHE_X4_OP(0, 1, NULL, 0),
> +		SPINAND_PAGE_READ_FROM_CACHE_X2_OP(0, 1, NULL, 0),
> +		SPINAND_PAGE_READ_FROM_CACHE_OP(true, 0, 1, NULL, 0),
> +		SPINAND_PAGE_READ_FROM_CACHE_OP(false, 0, 1, NULL, 0));
> +
> +static SPINAND_OP_VARIANTS(write_cache_variants_mt29f2g01aaaed,
> +		SPINAND_PROG_LOAD(true, 0, NULL, 0));
> +
> +static SPINAND_OP_VARIANTS(update_cache_variants_mt29f2g01aaaed,
> +		SPINAND_PROG_LOAD(false, 0, NULL, 0));
> +

Okay, I'd suggest picking more generic names. How about renaming the
existing variants into quadio_read_cache_variants,
x4_write_cache_variants and x4_update_cache_variants and naming the new
ones x4_read_cache_variants, x1_write_cache_variants and
x1_update_cache_variants.

>  static int micron_8_ooblayout_ecc(struct mtd_info *mtd, int section,
>  				  struct mtd_oob_region *region)
>  {
> @@ -69,11 +85,41 @@ static int micron_8_ooblayout_free(struct mtd_info *mtd, int section,
>  	return 0;
>  }
>  
> +static int mt29f2g01aaaed_ooblayout_ecc(struct mtd_info *mtd, int section,
> +					struct mtd_oob_region *region)
> +{
> +	if (section >= 4)
> +		return -ERANGE;

Hm, I'd try to deduce the max section based on the
pagesize/ecc-step-size so we can re-use the same ooblayout def for different
pagesize/ecc-step-size combinations.

> +
> +	region->offset = (section * 16) + 8;
> +	region->length = 8;
> +
> +	return 0;
> +}
> +
> +static int mt29f2g01aaaed_ooblayout_free(struct mtd_info *mtd, int section,
> +					 struct mtd_oob_region *region)
> +{
> +	if (section >= 4)
> +		return -ERANGE;
> +
> +	/* Reserve 2 bytes for the BBM. */
> +	region->offset = (section * 16) + 2;

You should probably only reserve those 2 bytes in section 0 (where the
BBM is).

> +	region->length = 6;
> +
> +	return 0;
> +}
> +
>  static const struct mtd_ooblayout_ops micron_8_ooblayout = {
>  	.ecc = micron_8_ooblayout_ecc,
>  	.free = micron_8_ooblayout_free,
>  };
>  
> +static const struct mtd_ooblayout_ops mt29f2g01aaaed_ooblayout = {

Maybe name that one micron_interleaved_ooblayout, and rename
micron_8_ooblayout into micron_grouped_ooblayout.

> +	.ecc = mt29f2g01aaaed_ooblayout_ecc,
> +	.free = mt29f2g01aaaed_ooblayout_free,
> +};
> +
>  static int micron_select_target(struct spinand_device *spinand,
>  				unsigned int target)
>  {
> @@ -114,6 +160,27 @@ static int micron_8_ecc_get_status(struct spinand_device *spinand,
>  	return -EINVAL;
>  }
>  
> +static int mt29f2g01aaaed_ecc_get_status(struct spinand_device *spinand,
> +					 u8 status)
> +{
> +	switch (status & MICRON_STATUS_ECC_MASK) {
> +	case STATUS_ECC_NO_BITFLIPS:
> +		return 0;
> +
> +	case STATUS_ECC_UNCOR_ERROR:
> +		return -EBADMSG;
> +
> +	/* 1 to 4-bit error detected and corrected */
> +	case MICRON_STATUS_ECC_1TO4_BITFLIPS:
> +		return 4;
> +
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}

Looks like you're duplicating spinand_check_ecc_status(). Just leave the
get_status hook to NULL, that should do trick.