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Date:   Wed, 14 Feb 2018 20:15:41 +0100
From:   Boris Brezillon <boris.brezillon@bootlin.com>
To:     KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
Cc:     boris.brezillon@free-electrons.com, richard@nod.at,
        dwmw2@infradead.org, computersforpeace@gmail.com,
        marek.vasut@gmail.com, cyrille.pitchen@wedev4u.fr,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next v4] mtd: nand: toshiba: Retrieve ECC requirements
 from extended ID
Message-ID: <20180214201541.7c939976@bbrezillon>
In-Reply-To: <1518622506-16606-1-git-send-email-yoshitake.kobayashi@toshiba.co.jp>
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-linux-mmc
+linux-mtd

On Thu, 15 Feb 2018 00:35:06 +0900
KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp> wrote:

> This patch enables support to read the ECC strength and size from the
> NAND flash using Toshiba Memory SLC NAND extended-ID. This patch is
> based on the information of the 6th ID byte of the Toshiba Memory SLC
> NAND.

This version looks good to me.

> 
> Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
> ---
>  drivers/mtd/nand/nand_toshiba.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
> index 57df857..ab43f02 100644
> --- a/drivers/mtd/nand/nand_toshiba.c
> +++ b/drivers/mtd/nand/nand_toshiba.c
> @@ -35,6 +35,32 @@ static void toshiba_nand_decode_id(struct nand_chip *chip)
>  	    (chip->id.data[5] & 0x7) == 0x6 /* 24nm */ &&
>  	    !(chip->id.data[4] & 0x80) /* !BENAND */)
>  		mtd->oobsize = 32 * mtd->writesize >> 9;
> +
> +	/*
> +	 * Extract ECC requirements from 6th id byte.
> +	 * For Toshiba SLC, ecc requrements are as follows:
> +	 *  - 43nm: 1 bit ECC for each 512Byte is required.
> +	 *  - 32nm: 4 bit ECC for each 512Byte is required.
> +	 *  - 24nm: 8 bit ECC for each 512Byte is required.
> +	 */
> +	if (chip->id.len >= 6 && nand_is_slc(chip)) {
> +		chip->ecc_step_ds = 512;
> +		switch (chip->id.data[5] & 0x7) {
> +		case 0x4:
> +			chip->ecc_strength_ds = 1;
> +			break;
> +		case 0x5:
> +			chip->ecc_strength_ds = 4;
> +			break;
> +		case 0x6:
> +			chip->ecc_strength_ds = 8;
> +			break;
> +		default:
> +			WARN(1, "Could not get ECC info");
> +			chip->ecc_step_ds = 0;
> +			break;
> +		}
> +	}
>  }
>  
>  static int toshiba_nand_init(struct nand_chip *chip)


-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com