linux-kernel - Re: [PATCH 3/3] mtd: spinand: Wait for the erase op to finish before writing a bad block marker

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Message-ID: <20200217113919.0508acc4@xps13>
Date:   Mon, 17 Feb 2020 11:39:19 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
Cc:     Boris Brezillon <bbrezillon@...nel.org>,
        Jeff Kletsky <git-commits@...ycomm.com>,
        liaoweixiong <liaoweixiong@...winnertech.com>,
        Peter Pan <peterpandong@...ron.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "Richard Weinberger" <richard@....at>
Subject: Re: [PATCH 3/3] mtd: spinand: Wait for the erase op to finish
 before writing a bad block marker

Hi Frieder,

Schrempf Frieder <frieder.schrempf@...tron.de> wrote on Tue, 11 Feb
2020 16:35:53 +0000:

> From: Frieder Schrempf <frieder.schrempf@...tron.de>
> 
> Currently when marking a block, we use spinand_erase_op() to erase
> the block before writing the marker to the OOB area without waiting
> for the operation to succeed. This can lead to the marking failing
> silently and no bad block marker being written to the flash.
> 
> To fix this we reuse the spinand_erase() function, that already does
> everything we need to do before actually writing the marker.
> 

Thanks a lot for this series!

Yet I don't really understand the point of waiting for the erasure if
it failed: we don't really care as programming (1 -> 0) cells is always
possible. Are you sure this lead to an error?

Also, why just not calling spinand_erase() instead of
spinand_erase_op() from spinand_markbad()?

> Fixes: 7529df465248 ("mtd: nand: Add core infrastructure to support SPI NANDs")
> Cc: stable@...r.kernel.org
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> ---
>  drivers/mtd/nand/spi/core.c | 56 ++++++++++++++++++-------------------
>  1 file changed, 28 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 925db6269861..8a69d13639e2 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -600,6 +600,32 @@ static int spinand_mtd_block_isbad(struct mtd_info *mtd, loff_t offs)
>  	return ret;
>  }
>  
> +static int __spinand_erase(struct nand_device *nand, const struct nand_pos *pos,
> +			   bool hard_fail)
> +{
> +	struct spinand_device *spinand = nand_to_spinand(nand);
> +	u8 status;
> +	int ret;
> +
> +	ret = spinand_select_target(spinand, pos->target);
> +	if (ret)
> +		return ret;
> +
> +	ret = spinand_write_enable_op(spinand);
> +	if (ret)
> +		return ret;
> +
> +	ret = spinand_erase_op(spinand, pos);
> +	if (ret && hard_fail)
> +		return ret;
> +
> +	ret = spinand_wait(spinand, &status);
> +	if (!ret && (status & STATUS_ERASE_FAILED))
> +		ret = -EIO;
> +
> +	return ret;
> +}
> +
>  static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
>  {
>  	struct spinand_device *spinand = nand_to_spinand(nand);
> @@ -614,16 +640,10 @@ static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
>  	int ret;
>  
>  	/* Erase block before marking it bad. */
> -	ret = spinand_select_target(spinand, pos->target);
> -	if (ret)
> -		return ret;
> -
> -	ret = spinand_write_enable_op(spinand);
> +	ret = __spinand_erase(nand, pos, false);
>  	if (ret)
>  		return ret;
>  
> -	spinand_erase_op(spinand, pos);
> -
>  	return spinand_write_page(spinand, &req);
>  }
>  
> @@ -644,27 +664,7 @@ static int spinand_mtd_block_markbad(struct mtd_info *mtd, loff_t offs)
>  
>  static int spinand_erase(struct nand_device *nand, const struct nand_pos *pos)
>  {
> -	struct spinand_device *spinand = nand_to_spinand(nand);
> -	u8 status;
> -	int ret;
> -
> -	ret = spinand_select_target(spinand, pos->target);
> -	if (ret)
> -		return ret;
> -
> -	ret = spinand_write_enable_op(spinand);
> -	if (ret)
> -		return ret;
> -
> -	ret = spinand_erase_op(spinand, pos);
> -	if (ret)
> -		return ret;
> -
> -	ret = spinand_wait(spinand, &status);
> -	if (!ret && (status & STATUS_ERASE_FAILED))
> -		ret = -EIO;
> -
> -	return ret;
> +	return __spinand_erase(nand, pos, true);
>  }
>  
>  static int spinand_mtd_erase(struct mtd_info *mtd,

Thanks,
Miquèl