Re: [PATCH v2 7/9] mtd: rawnand: onfi: Drop a useless parameter page read

[Boris Brezillon <boris.brezillon@collabora.com>]

On Fri, 24 Apr 2020 18:40:40 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> During detection the logic on the NAND bus is:
> 
>     /* Regular ONFI detection */
>     1/ read the three NAND parameter pages
> 
>     /* Extended parameter page detection */
>     2/ send "read the NAND parameter page" commands without reading
>        actual data
>     3/ move the column pointer to the extended page and read it
> 
> If fact, as long as there is nothing happening on the NAND bus between
> 1/ and 3/, the operation 2/ is redundant so remove it.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/mtd/nand/raw/nand_onfi.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
> index 6576b841bc56..2fc71b7c361f 100644
> --- a/drivers/mtd/nand/raw/nand_onfi.c
> +++ b/drivers/mtd/nand/raw/nand_onfi.c
> @@ -47,12 +47,10 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
>  	if (!ep)
>  		return -ENOMEM;
>  
> -	/* Send our own NAND_CMD_PARAM. */
> -	ret = nand_read_param_page_op(chip, 0, NULL, 0);
> -	if (ret)
> -		goto ext_out;
> -
> -	/* Use the Change Read Column command to skip the ONFI param pages. */
> +	/*
> +	 * Use the Change Read Column command to skip the ONFI param pages and
> +	 * ensure we read at the right location.
> +	 */
>  	ret = nand_change_read_column_op(chip,
>  					 sizeof(*p) * p->num_of_param_pages,
>  					 ep, len, true);


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