Re: [PATCH v3 09/13] mtd: rawnand: onfi: Adapt the parameter page read to constraint controllers

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

On Mon,  4 May 2020 10:24:10 +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 simple 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.
> 
> Let's use a regular PARAMETER PAGE READ operation for the first
> iteration and use either a CHANGE READ COLUMN or a simple DATA READ
> operation for the following copies, depending on what the controller
> supports. The default behavior for non-exec-op compliant drivers
> remains the same: DATA READ.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_onfi.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
> index e6ffbe8c9a0c..49cb04c02e9f 100644
> --- a/drivers/mtd/nand/raw/nand_onfi.c
> +++ b/drivers/mtd/nand/raw/nand_onfi.c
> @@ -143,6 +143,7 @@ int nand_onfi_detect(struct nand_chip *chip)
>  	struct nand_memory_organization *memorg;
>  	struct nand_onfi_params *p = NULL, *pbuf;
>  	struct onfi_params *onfi;
> +	bool use_datain = false;
>  	int onfi_version = 0;
>  	char id[4];
>  	int i, ret, val;
> @@ -160,15 +161,21 @@ 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;
> -	}
> +	if (!nand_has_exec_op(chip) ||
> +	    (nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true) == 0))

Just nitpicking, but isn't checkpatch complaining about unneeded parens?
Any reason you didn't use

	    !nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true)

here?

The rest looks good,

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

> +		use_datain = true;
>  
>  	for (i = 0; i < ONFI_PARAM_PAGES; i++) {
> -		ret = nand_read_data_op(chip, &pbuf[i], sizeof(*pbuf), true,
> -					false);
> +		if (!i)
> +			ret = nand_read_param_page_op(chip, 0, &pbuf[i],
> +						      sizeof(*pbuf));
> +		else if (use_datain)
> +			ret = nand_read_data_op(chip, &pbuf[i], sizeof(*pbuf),
> +						true, false);
> +		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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