Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 4 Jul 2023 17:13:48 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Johan Jonker <jbx6244@gmail.com>
Cc:     richard@nod.at, vigneshr@ti.com, heiko@sntech.de,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, yifeng.zhao@rock-chips.com
Subject: Re: [PATCH v3 3/3] mtd: rawnand: rockchip-nand-controller: add
 skipbbt option
Message-ID: <20230704171348.5eee98f7@xps-13>
In-Reply-To: <457c1da7-61dc-2a56-4f86-47413795138c@gmail.com>
References: <0047fc52-bc45-a768-8bdd-c0f12cddc17e@gmail.com>
        <457c1da7-61dc-2a56-4f86-47413795138c@gmail.com>
Organization: Bootlin
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi Johan,

jbx6244@gmail.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.

>=20
> Signed-off-by: Johan Jonker <jbx6244@gmail.com>
> ---
>=20
> Changes V3:
>   Change prefixes
>=20
> Changed V2:
>   reword
>=20
> ---
>=20
> 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
>=20
> So we keep it include in this serie.
> ---
>  drivers/mtd/nand/raw/rockchip-nand-controller.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>=20
> diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mt=
d/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;
>  };
>=20
> +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,
>=20
>  	nand_set_controller_data(chip, nfc);
>=20
> +	if (skipbbt)
> +		chip->options |=3D NAND_SKIP_BBTSCAN | NAND_NO_BBM_QUIRK;
> +
>  	chip->options |=3D NAND_USES_DMA | NAND_NO_SUBPAGE_WRITE;
>  	chip->bbt_options =3D NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB;
>=20
> --
> 2.30.2
>=20


Thanks,
Miqu=C3=A8l