linux-kernel - Re: [RESEND: PATCH v1] mtd: nand: davinci: add support for 4K page size nand devices.

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Message-ID: <20150720165804.GA24125@google.com>
Date:	Mon, 20 Jul 2015 09:58:04 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	Murali Karicheri <m-karicheri2@...com>
Cc:	dwmw2@...radead.org, wsa@...-dreams.de,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND: PATCH v1] mtd: nand: davinci: add support for 4K page
 size nand devices.

+ others

On Mon, Jul 13, 2015 at 04:07:16PM -0400, Murali Karicheri wrote:
> K2L EVM uses NAND with 4K page size. This patch add support for
> ECC layout requires to enable Micron MT29F16G08ADBCAH4 NAND available
> on this EVM.
> 
> Signed-off-by: Murali Karicheri <m-karicheri2@...com>
> Signed-off-by: Hao Zhang <hzhang@...com>

I see a much earlier patch that is nearly identical, but whose
whitespace is a little cleaner:

http://patchwork.ozlabs.org/patch/381347/

I don't know why it was never ack'd or merged. I think I'll take it now.

Is there anyone who wants to step and have a MAINTAINERS entry on this?
I don't have hardware or anything, so it'd be great if someone who works
on these things can ack changes for davinci_nand.c.

Thanks,
Brian

> ---
>  - Resend after subscribing to linux-mtd mailing list. I assume
>    no one has seen this on this mailing list as I don't have any
>    comments. So re-sending.
>  - v1 - Remove the comment as well from the code as now 4K page
>    is supported
>  drivers/mtd/nand/davinci_nand.c | 42 +++++++++++++++++++++++++++++------------
>  1 file changed, 30 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index feb6d18..90b177b 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -520,6 +520,31 @@ static struct nand_ecclayout hwecc4_2048 = {
>  	},
>  };
>  
> +/* An ECC layout for using 4-bit ECC with large-page (4096bytes) flash,
> + * storing ten ECC bytes plus the manufacturer's bad block marker byte,
> + * and not overlapping the default BBT markers.
> + */
> +static struct nand_ecclayout hwecc4_4096 = {
> +	.eccbytes = 80,
> +	.eccpos = {
> +		/* at the end of spare sector */
> +		48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
> +		58, 59, 60, 61, 62, 63, 64, 65, 66, 67,
> +		68, 69, 70, 71, 72, 73, 74, 75, 76, 77,
> +		78, 79, 80, 81, 82, 83, 84, 85, 86, 87,
> +		88, 89, 90, 91, 92, 93, 94, 95, 96, 97,
> +		98, 99, 100, 101, 102, 103, 104, 105, 106, 107,
> +		108, 109, 110, 111, 112, 113, 114, 115, 116, 117,
> +		118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
> +		},
> +	.oobfree = {
> +		/* 2 bytes at offset 0 hold manufacturer badblock markers */
> +		{.offset = 2, .length = 46, },
> +		/* 5 bytes at offset 8 hold BBT markers */
> +		/* 8 bytes at offset 16 hold JFFS2 clean markers */
> +	},
> +};
> +
>  #if defined(CONFIG_OF)
>  static const struct of_device_id davinci_nand_of_match[] = {
>  	{.compatible = "ti,davinci-nand", },
> @@ -796,18 +821,11 @@ static int nand_davinci_probe(struct platform_device *pdev)
>  			info->chip.ecc.mode = NAND_ECC_HW_OOB_FIRST;
>  			goto syndrome_done;
>  		}
> -
> -		/* 4KiB page chips are not yet supported. The eccpos from
> -		 * nand_ecclayout cannot hold 80 bytes and change to eccpos[]
> -		 * breaks userspace ioctl interface with mtd-utils. Once we
> -		 * resolve this issue, NAND_ECC_HW_OOB_FIRST mode can be used
> -		 * for the 4KiB page chips.
> -		 *
> -		 * TODO: Note that nand_ecclayout has now been expanded and can
> -		 *  hold plenty of OOB entries.
> -		 */
> -		dev_warn(&pdev->dev, "no 4-bit ECC support yet "
> -				"for 4KiB-page NAND\n");
> +		if (chunks == 8) {
> +			info->ecclayout = hwecc4_4096;
> +			info->chip.ecc.mode = NAND_ECC_HW_OOB_FIRST;
> +			goto syndrome_done;
> +		}
>  		ret = -EIO;
>  		goto err;
>  
> -- 
> 1.9.1
> 
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