Re: [PATCH v2 1/3] mtd: rawnand: Add the nand_chip->erase hook

From: Boris Brezillon <boris.brezillon@collabora.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Richard Weinberger <richard@nod.at>,
	Zoltan Szubbocsev <zszubbocsev@micron.com>,
	linux-mtd@lists.infradead.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	tglx@linutronix.de,
	Piotr Wojtaszczyk <WojtaszczykP@cumminsallison.com>,
	Bean Huo <beanhuo@micron.com>
Subject: Re: [PATCH v2 1/3] mtd: rawnand: Add the nand_chip->erase hook
Date: Sun, 3 May 2020 17:01:46 +0200	[thread overview]
Message-ID: <20200503170146.1bbf07fe@collabora.com> (raw)
In-Reply-To: <20200503114029.30257-2-miquel.raynal@bootlin.com>

On Sun,  3 May 2020 13:40:27 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> In order to solve an issue with Micron NANDs, we must be able to
> overload the erase operation. With this in mind, we create a ->erase
> hook in the nand_chip structure which points by default to the
> currently in use nand_erase_nand() helper.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c | 6 +++++-
>  include/linux/mtd/rawnand.h      | 3 +++
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index c24e5e2ba130..7c7ac722d88b 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -4158,7 +4158,9 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to,
>   */
>  static int nand_erase(struct mtd_info *mtd, struct erase_info *instr)
>  {
> -	return nand_erase_nand(mtd_to_nand(mtd), instr, 0);
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +
> +	return chip->erase(chip, instr, 0);
>  }
>  
>  /**
> @@ -4419,6 +4421,8 @@ static void nand_set_defaults(struct nand_chip *chip)
>  
>  	if (!chip->buf_align)
>  		chip->buf_align = 1;
> +
> +	chip->erase = nand_erase_nand;
>  }
>  
>  /* Sanitize ONFI strings so we can safely print them */
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 1e76196f9829..505c13f7a2ba 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -1020,6 +1020,7 @@ struct nand_legacy {
>   *			avoid using them.
>   * @setup_read_retry:	[FLASHSPECIFIC] flash (vendor) specific function for
>   *			setting the read-retry mode. Mostly needed for MLC NAND.
> + * @erase:		Raw NAND erase operation.
>   * @ecc:		[BOARDSPECIFIC] ECC control structure
>   * @buf_align:		minimum buffer alignment required by a platform
>   * @oob_poi:		"poison value buffer," used for laying out OOB data
> @@ -1089,6 +1090,8 @@ struct nand_chip {
>  	struct nand_legacy legacy;
>  
>  	int (*setup_read_retry)(struct nand_chip *chip, int retry_mode);
> +	int (*erase)(struct nand_chip *chip, struct erase_info *instr,
> +		     int allowbbt);
>  

Before we do that, can we create a nand_chip_ops struct and place all
NAND-specific ops in there?

Regarding the erase hook itself, I wonder if it wouldn't be simpler to
have optional {pre,post}_erase() hooks instead (I think makes even more
sense for the ->write_oob() hook).

>  	unsigned int options;
>  	unsigned int bbt_options;

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