[PATCH 2/3] mtd: rawnand: Check the CHANGE_READ_COLUMN from nand_read_subpage() is supported

[Boris Brezillon]

On Mon,  6 Sep 2021 15:29:41 +0200
Miquel Raynal <miquel.raynal at bootlin.com> wrote:

> There are constraint controllers which do not support
> CHANGE_READ_COLUMNs at any offset. In particular, the offset alignment
> might be an issue. Ensure that the operation is supported before trying
> it.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 7f29f27bb6fd..8175635b9802 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -3065,10 +3065,19 @@ static int nand_read_subpage(struct nand_chip *chip, uint32_t data_offs,
>  		    (busw - 1))
>  			aligned_len++;
>  
> -		ret = nand_change_read_column_op(chip,
> -						 mtd->writesize + aligned_pos,
> -						 &chip->oob_poi[aligned_pos],
> -						 aligned_len, false);
> +		ret = nand_check_change_read_column_op(chip,
> +						       mtd->writesize + aligned_pos,
> +						       &chip->oob_poi[aligned_pos],
> +						       aligned_len, false, true);
> +		if (!ret)
> +			ret = nand_change_read_column_op(chip,
> +							 mtd->writesize + aligned_pos,
> +							 &chip->oob_poi[aligned_pos],
> +							 aligned_len, false);
> +		else
> +			ret = nand_change_read_column_op(chip, mtd->writesize,
> +							 chip->oob_poi,
> +							 mtd->oobsize, false);
>  		if (ret)
>  			return ret;

So you just fail if the CHANGE column op is not supported? Looks like
this check should be done before we assign ecc->read_subpage to
nand_read_subpage in
nand_set_ecc_on_host_ops()/nand_set_ecc_soft_ops()...

>  	}