Re: [PATCH v2] mtd: nand: samsung: Disable subpage writes on E-die NAND

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Tue, 9 Jan 2018 14:19:11 +0100
Ladislav Michl <ladis@linux-mips.org> wrote:

> Samsung E-die SLC NAND manufactured using 21nm process (K9F1G08U0E)
> does not support partial page programming, so disable subpage writes
> for it. Manufacturing process is stored in lowest two bits of 5th ID
> byte.

Applied.

Thanks,

Boris

> 
> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> ---
>  Changes:
>  - v2: 
>    * Reword commit log
>    * Check also for device type
>    * Reimplement if statements using switch
> 
>  drivers/mtd/nand/nand_samsung.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_samsung.c b/drivers/mtd/nand/nand_samsung.c
> index f6b0a63a068c..6971c35b78e9 100644
> --- a/drivers/mtd/nand/nand_samsung.c
> +++ b/drivers/mtd/nand/nand_samsung.c
> @@ -92,10 +92,22 @@ static void samsung_nand_decode_id(struct nand_chip *chip)
>  	} else {
>  		nand_decode_ext_id(chip);
>  
> -		/* Datasheet values for SLC Samsung K9F4G08U0D-S[I|C]B0(T00) */
> -		if (nand_is_slc(chip) && chip->id.data[1] == 0xDC) {
> -			chip->ecc_step_ds = 512;
> -			chip->ecc_strength_ds = 1;
> +		if (nand_is_slc(chip)) {
> +			switch (chip->id.data[1]) {
> +			/* K9F4G08U0D-S[I|C]B0(T00) */
> +			case 0xDC:
> +				chip->ecc_step_ds = 512;
> +				chip->ecc_strength_ds = 1;
> +				break;
> +			/* K9F1G08U0E 21nm chips do not support subpage write */
> +			case 0xF1:
> +				if (chip->id.len > 4 &&
> +				    (chip->id.data[4] & GENMASK(1,0)) == 0x1)
> +					chip->options |= NAND_NO_SUBPAGE_WRITE;
> +				break;
> +			default:
> +				break;
> +			}
>  		}
>  	}
>  }