Re: [PATCH v3 10/13] mtd: rawnand: jedec: Adapt the parameter page read to constraint controllers

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

On Mon,  4 May 2020 10:24:11 +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.
> 
> Let's use a regular PARAMETER PAGE READ operation for the first
> iteration and use eithe a CHANGE READ COLUMN or a simple DATA READ
> operation for the following copies, depending on what the controller
> supports. The default for non-exec-op compliant drivers remains
> unchanged: use a SIMPLE READ.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_jedec.c | 34 ++++++++++++++++++++-----------
>  1 file changed, 22 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_jedec.c b/drivers/mtd/nand/raw/nand_jedec.c
> index 63069f1948a8..be270b36317e 100644
> --- a/drivers/mtd/nand/raw/nand_jedec.c
> +++ b/drivers/mtd/nand/raw/nand_jedec.c
> @@ -25,8 +25,9 @@ int nand_jedec_detect(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	struct nand_memory_organization *memorg;
> -	struct nand_jedec_params *p;
> +	struct nand_jedec_params *p = NULL, *pbuf;
>  	struct jedec_ecc_info *ecc;
> +	bool use_datain = false;
>  	int jedec_version = 0;
>  	char id[5];
>  	int i, val, ret;
> @@ -40,25 +41,32 @@ int nand_jedec_detect(struct nand_chip *chip)
>  		return 0;
>  
>  	/* JEDEC chip: allocate a buffer to hold its parameter page */
> -	p = kzalloc(sizeof(*p), GFP_KERNEL);
> -	if (!p)
> +	pbuf = kzalloc(sizeof(*pbuf) * JEDEC_PARAM_PAGES, GFP_KERNEL);
> +	if (!pbuf)
>  		return -ENOMEM;
>  
> -	ret = nand_read_param_page_op(chip, 0x40, NULL, 0);
> -	if (ret) {
> -		ret = 0;
> -		goto free_jedec_param_page;
> -	}
> +	if (!nand_has_exec_op(chip) ||
> +	    (nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true) == 0))
> +		use_datain = true;
>  
>  	for (i = 0; i < JEDEC_PARAM_PAGES; i++) {
> -		ret = nand_read_data_op(chip, p, sizeof(*p), true, false);
> +		if (!i)
> +			ret = nand_read_param_page_op(chip, 0x40, &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);

Now that you only ever read a page at a time, and given you don't do
the majority_bit() thing when all pages are corrupted, I'd suggest
sticking to one sizeof(*p) allocation and getting rid of the pbuf var.

But it's not a big deal, so feel free to add

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

if you don't want to send a new version.

>  		if (ret) {
>  			ret = 0;
>  			goto free_jedec_param_page;
>  		}
>  
> -		crc = onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 510);
> -		if (crc == le16_to_cpu(p->crc))
> +		crc = onfi_crc16(ONFI_CRC_BASE, (u8 *)&pbuf[i], 510);
> +		if (crc == le16_to_cpu(pbuf[i].crc))
>  			break;
>  	}
>  
> @@ -67,6 +75,8 @@ int nand_jedec_detect(struct nand_chip *chip)
>  		goto free_jedec_param_page;
>  	}
>  
> +	p = &pbuf[i];
> +
>  	/* Check version */
>  	val = le16_to_cpu(p->revision);
>  	if (val & (1 << 2))
> @@ -122,6 +132,6 @@ int nand_jedec_detect(struct nand_chip *chip)
>  	ret = 1;
>  
>  free_jedec_param_page:
> -	kfree(p);
> +	kfree(pbuf);
>  	return ret;
>  }


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