linux-kernel - Re: [PATCH v1 2/2] mtd: rawnand: add nand-skip-bbtscan and nand-no-bbm-quirk DT options

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Date:   Sat, 15 Jul 2023 17:55:38 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Johan Jonker <jbx6244@...il.com>
Cc:     richard@....at, vigneshr@...com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v1 2/2] mtd: rawnand: add nand-skip-bbtscan and
 nand-no-bbm-quirk DT options

Hi Johan,

jbx6244@...il.com wrote on Sat, 15 Jul 2023 12:49:18 +0200:

> A NAND chip can contain a different data format then the MTD framework
> expects in the erase blocks for the Bad Block Table(BBT).
> Result is a failed probe, while nothing wrong with the hardware.
> Some MTD flags need to be set to gain access again.
> 
> 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.
> 
> Add nand-skip-bbtscan and nand-no-bbm-quirk Device Tree options,
> so the user has the "freedom of choice" by neutral
> access mode to read and write in whatever format is needed.

This sounds like a partial solution. How do you handle bad blocks?

> Signed-off-by: Johan Jonker <jbx6244@...il.com>
> ---
> 
> Previous discussion:
> [PATCH v3 3/3] mtd: rawnand: rockchip-nand-controller: add skipbbt option
> https://lore.kernel.org/linux-mtd/1618382560.2326931.1689261435022.JavaMail.zimbra@nod.at/
> ---
>  drivers/mtd/nand/raw/nand_base.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index a6af521832aa..f0fa5c3519b1 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -5521,6 +5521,12 @@ static int rawnand_dt_init(struct nand_chip *chip)
>  	if (of_property_read_bool(dn, "nand-is-boot-medium"))
>  		chip->options |= NAND_IS_BOOT_MEDIUM;
> 
> +	if (of_property_read_bool(dn, "nand-no-bbm-quirk"))
> +		chip->options |= NAND_NO_BBM_QUIRK;
> +
> +	if (of_property_read_bool(dn, "nand-skip-bbtscan"))
> +		chip->options |= NAND_SKIP_BBTSCAN;
> +
>  	if (of_property_read_bool(dn, "nand-on-flash-bbt"))
>  		chip->bbt_options |= NAND_BBT_USE_FLASH;
> 
> --
> 2.30.2
> 


Thanks,
Miquèl