linux-kernel - Re: [RFC PATCH 2/2] mtd: rawnand: marvell: Support page size of 2048 with 8-bit ECC

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Message-ID: <20180618153703.77bc01c1@xps13>
Date:   Mon, 18 Jun 2018 15:37:03 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     boris.brezillon@...tlin.com, dwmw2@...radead.org,
        computersforpeace@...il.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>,
        Marek Vasut <marek.vasut@...il.com>
Subject: Re: [RFC PATCH 2/2] mtd: rawnand: marvell: Support page size of
 2048 with 8-bit ECC

Hi Chris,

On Mon, 18 Jun 2018 16:52:55 +1200, Chris Packham
<chris.packham@...iedtelesis.co.nz> wrote:

> The MT29F1G08ABAFAWP-ITE:F chip has 2048 byte pages and requires a
> minimum ECC strength of 8-bits. Allow for this combination of
> requirements using the marvell_nand controller.
> 
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> ---
> I've tried to follow the recommended AN-379 from Marvell. They do seem
> to have information that covers this particular set of chip requirements
> but I'm not confident I've translated their code correctly into the
> current marvell_nand implementation.
> 
> This is enough to make the nand_scan work but ubi/ubifs fails to initialise
> and/or mount so I may have something completely wrong. This may also be
> because this chip has internal ECC enabled which cannot be disabled. I
> turned up an old thread on this from April last year[1] but I didn't see
> anything resulting from this. Can this combination of ECC
> implementations even co-exist?
> 
> [1] - http://lists.infradead.org/pipermail/linux-mtd/2017-April/073370.html
> 
>  drivers/mtd/nand/raw/marvell_nand.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/nand/raw/marvell_nand.c b/drivers/mtd/nand/raw/marvell_nand.c
> index ebb1d141b900..5712df553a8e 100644
> --- a/drivers/mtd/nand/raw/marvell_nand.c
> +++ b/drivers/mtd/nand/raw/marvell_nand.c
> @@ -217,6 +217,7 @@ static const struct marvell_hw_ecc_layout marvell_nfc_layouts[] = {
>  	MARVELL_LAYOUT(  512,   512,  1,  1,  1,  512,  8,  8,  0,  0,  0),
>  	MARVELL_LAYOUT( 2048,   512,  1,  1,  1, 2048, 40, 24,  0,  0,  0),
>  	MARVELL_LAYOUT( 2048,   512,  4,  1,  1, 2048, 32, 30,  0,  0,  0),
> +	MARVELL_LAYOUT( 2048,   512,  8,  1,  1, 1024, 0, 30,  1024,  32,  30),

I suppose you should not use HW_ECC for this chip. Hence this line is
useless. However I think it should be:

	MARVELL_LAYOUT( 2048,   512,  8,  2,  1, 1024, 0, 30, 1024, 32,	30),

                                          ^

>  	MARVELL_LAYOUT( 4096,   512,  4,  2,  2, 2048, 32, 30,  0,  0,  0),
>  	MARVELL_LAYOUT( 4096,   512,  8,  5,  4, 1024,  0, 30,  0, 64, 30),
>  };

Regards,
Miquèl