Re: [PATCH v2 07/11] mtd: rawnand: onfi: Adapt the parameter page read to constraint controllers

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

On Wed, 29 Apr 2020 17:55:36 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> We already know that there are controllers not able to read the three
> copies of the parameter page in one go. The workaround was to first
> request the controller to assert command and address cycles on the
> NAND bus to trigger a parameter page read, and then do a read
> operation for each page.
> 
> But there are also controllers which are not able to split the
> parameter page read between the command/address cycles and the actual
> data operation.
> 
> All controllers are expected to be able to change the read column
> though. So let's use a regular parameter page read operation for the
> first iteration and use a change read column operation for the
> following copies.
> 
> The extra command and address cycles sent over the NAND bus are
> negligible compared to the amount of data that is being transferred
> anyway.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

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

> ---
>  drivers/mtd/nand/raw/nand_onfi.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
> index ee0f2c2549c1..19e1be94c7e3 100644
> --- a/drivers/mtd/nand/raw/nand_onfi.c
> +++ b/drivers/mtd/nand/raw/nand_onfi.c
> @@ -160,14 +160,14 @@ int nand_onfi_detect(struct nand_chip *chip)
>  	if (!pbuf)
>  		return -ENOMEM;
>  
> -	ret = nand_read_param_page_op(chip, 0, NULL, 0);
> -	if (ret) {
> -		ret = 0;
> -		goto free_onfi_param_page;
> -	}
> -
>  	for (i = 0; i < ONFI_PARAM_PAGES; i++) {
> -		ret = nand_read_data_op(chip, &pbuf[i], sizeof(*pbuf), true);
> +		if (!i)
> +			ret = nand_read_param_page_op(chip, 0, &pbuf[i],
> +						      sizeof(*pbuf));
> +		else
> +			ret = nand_change_read_column_op(chip, sizeof(*pbuf) * i,
> +							 &pbuf[i], sizeof(*pbuf),
> +							 true);
>  		if (ret) {
>  			ret = 0;
>  			goto free_onfi_param_page;


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