linux-kernel - Re: [PATCH v1 2/5] mtd: nand: raw: rockchip-nand-controller: add skipbbt option

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Date:   Fri, 9 Jun 2023 10:44:26 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Johan Jonker <jbx6244@...il.com>
Cc:     richard@....at, vigneshr@...com, heiko@...ech.de,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, yifeng.zhao@...k-chips.com
Subject: Re: [PATCH v1 2/5] mtd: nand: raw: rockchip-nand-controller: add
 skipbbt option

Hi Johan,

jbx6244@...il.com wrote on Thu, 8 Jun 2023 18:30:27 +0200:

> On Rockchip SoCs the first boot stages are written on NAND
> with help of manufacturer software that uses a different format
> then the MTD framework. Skip the automatic BBT scan with the
> NAND_SKIP_BBTSCAN option so we can run it manually.

How do you run it manually?

> The NAND_NO_BBM_QUIRK option allows us to erase bad blocks with
> the nand_erase_nand() function and the flash_erase command.

For erasure you now have access to a debugfs entry for
experts/forensics which allows you to bypass all bad block checks.

> 
> Signed-off-by: Johan Jonker <jbx6244@...il.com>
> ---
>  drivers/mtd/nand/raw/rockchip-nand-controller.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> index cafccc324..f56430f6c 100644
> --- a/drivers/mtd/nand/raw/rockchip-nand-controller.c
> +++ b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> @@ -188,6 +188,10 @@ struct rk_nfc {
>  	unsigned long assigned_cs;
>  };
> 
> +static int skipbbt;
> +module_param(skipbbt, int, 0644);
> +MODULE_PARM_DESC(skipbbt, "Skip BBT scan if the NAND chip contains data not in MTD format.");

I highly dislike this.

It's not a module parameter that you need, it is related to a partition.

> +
>  static inline struct rk_nfc_nand_chip *rk_nfc_to_rknand(struct nand_chip *chip)
>  {
>  	return container_of(chip, struct rk_nfc_nand_chip, chip);
> @@ -1156,6 +1160,10 @@ static int rk_nfc_nand_chip_init(struct device *dev, struct rk_nfc *nfc,
> 
>  	nand_set_controller_data(chip, nfc);
> 
> +	/* Skip the automatic BBT scan so we can run it manually. */
> +	if (skipbbt)
> +		chip->options |= NAND_SKIP_BBTSCAN | NAND_NO_BBM_QUIRK;
> +
>  	chip->options |= NAND_USES_DMA | NAND_NO_SUBPAGE_WRITE;
>  	chip->bbt_options = NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB;
> 
> --
> 2.30.2
> 


Thanks,
Miquèl