linux-kernel - Re: [PATCH v3 3/3] mtd: rawnand: rockchip-nand-controller: add skipbbt option

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Date:   Tue, 4 Jul 2023 17:13:48 +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 v3 3/3] mtd: rawnand: rockchip-nand-controller: add
 skipbbt option

Hi Johan,

jbx6244@...il.com wrote on Thu, 15 Jun 2023 19:34:26 +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 that the original content is unchanged
> during the driver probe.
> The NAND_NO_BBM_QUIRK option allows us to erase bad blocks with
> the nand_erase_nand() function and the flash_erase command.
> With these options the user has the "freedom of choice" by neutral
> access mode to read and write in whatever format is needed.

Can the boot_rom_mode thing help?

For writing this part you can disable the bad block protection using
debugfs and then write an externally processed file in raw mode I guess.

For the boot I think I proposed a DT property. I don't remember how far
the discussion went.

> 
> Signed-off-by: Johan Jonker <jbx6244@...il.com>
> ---
> 
> Changes V3:
>   Change prefixes
> 
> Changed V2:
>   reword
> 
> ---
> 
> I'm aware that the maintainer finds it "awful",
> but it's absolute necessary to:
> 1: read/write boot blocks in user space without touching original content
> 2: format a NAND for MTD either with built in or external driver module
> 
> So we keep it include in this serie.
> ---
>  drivers/mtd/nand/raw/rockchip-nand-controller.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mtd/nand/raw/rockchip-nand-controller.c
> index 5a0468034..fcda4c760 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 data on the NAND chip is not in MTD format.");
> +
>  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);
> @@ -1153,6 +1157,9 @@ static int rk_nfc_nand_chip_init(struct device *dev, struct rk_nfc *nfc,
> 
>  	nand_set_controller_data(chip, nfc);
> 
> +	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