Re: [PATCH v2 1/1] mtd: rawnand: hynix: fix decoding the OOB size on H27UCG8T2BTR

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Sun, 24 Jun 2018 22:53:55 +0200
Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:

> The datasheet of the H27UCG8T2BTR states that this chip has a page size
> of "16,384 + 1,280(Spare) bytes". The description of the "4th Byte of
> Device Identifier Description" indicates that bits 6, 3 and 2 are
> encoding the "Redundant Area Size / 8KB", where 640 bytes is a value of
> 0x6 (110 in binary notation).
> 
> hynix_nand_extract_oobsize decodes an OOB size of 640 bytes for this
> chip. Kernel boot log extract before this patch:
> nand: Could not find valid ONFI parameter page; aborting
> nand: device found, Manufacturer ID: 0xad, Chip ID: 0xde
> nand: Hynix NAND 8GiB 3,3V 8-bit
> nand: 8192 MiB, MLC, erase size: 4096 KiB, page size: 16384,
>       OOB size: 640
> 
> However, based on the description in the datasheet we need to multiply
> the OOB size with 2, because it's "640 spare bytes per 8192 bytes page
> size" and this NAND chip has a page size of 16384 (= 2 * 8192). After
> this patch the kernel boot log reports:
> nand: Could not find valid ONFI parameter page; aborting
> nand: device found, Manufacturer ID: 0xad, Chip ID: 0xde
> nand: Hynix NAND 8GiB 3,3V 8-bit
> nand: 8192 MiB, MLC, erase size: 4096 KiB, page size: 16384,
>       OOB size: 1280
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

LGTM.

Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

Just out of curiosity, what do you plan to put on your MLC chip? I
guess you already know that UBI/UBIFS are not supporting MLC chips. Do
you use another FS or an FTL + a block FS?

> ---
>  drivers/mtd/nand/raw/nand_hynix.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_hynix.c b/drivers/mtd/nand/raw/nand_hynix.c
> index d542908a0ebb..8cbe77f447c7 100644
> --- a/drivers/mtd/nand/raw/nand_hynix.c
> +++ b/drivers/mtd/nand/raw/nand_hynix.c
> @@ -473,6 +473,19 @@ static void hynix_nand_extract_oobsize(struct nand_chip *chip,
>  			WARN(1, "Invalid OOB size");
>  			break;
>  		}
> +
> +		/*
> +		 * The datasheet of H27UCG8T2BTR mentions that the "Redundant
> +		 * Area Size" is encoded "per 8KB" (page size). This chip uses
> +		 * a page size of 16KiB. The datasheet mentions an OOB size of
> +		 * 1.280 bytes, but the OOB size encoded in the ID bytes (using
> +		 * the existing logic above) is 640 bytes.
> +		 * Update the OOB size for this chip by taking the value
> +		 * determined above and scaling it to the actual page size (so
> +		 * the actual OOB size for this chip is: 640 * 16k / 8k).
> +		 */
> +		if (chip->id.data[1] == 0xde)
> +			mtd->oobsize *= mtd->writesize / SZ_8K;
>  	}
>  }
>