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SubjectRe: [PATCH -next v3 1/2] mtd: nand: toshiba: Retrieve ECC requirements from extended ID
On Wed,  6 Dec 2017 23:04:57 +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.
>
> Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
> ---
> drivers/mtd/nand/nand_toshiba.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
> index 57df857..c2c141b 100644
> --- a/drivers/mtd/nand/nand_toshiba.c
> +++ b/drivers/mtd/nand/nand_toshiba.c
> @@ -35,6 +35,34 @@ 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;
> + }
> + } else if (chip->id.len < 6 && nand_is_slc(chip)) {
> + WARN(1, "Could not get ECC info, 6th nand id byte does not exist.");

I'm pretty sure you have old NAND chips that do not have 6bytes ids
(see the table here [1]), and printing a huge backtrace in this case is
probably not what you want.

If you're okay with dropping this else block, I'll do the change when
applying, no need to send a new version.

> + }
> }
>
> static int toshiba_nand_init(struct nand_chip *chip)

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