Re: [RESEND PATCH v2 28/53] mtd: nand: denali: support "nand-ecc-strength" DT property

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Thu, 23 Mar 2017 09:17:37 +0900
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:

> Historically, this driver tried to choose as big ECC strength as
> possible, but it would be reasonable to allow DT to set a particular
> ECC strength with "nand-ecc-strength" property.
> 
> Going forward, DT platforms should specify "nand-ecc-strength" or
> "nand-ecc-maximize" to show the ECC strength strategy explicitly.
> 
> If nothing is specified in DT, "nand-ecc-maximize" is implied since
> this was the original behavior.

I would expect the ->ecc_xxx_ds information to be taken into account
when nand-ecc-strength and nand-ecc-maximize are missing (see my reply
to patch 26).

> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Acked-by: Rob Herring <robh@kernel.org>
> ---
> 
> Changes in v2:
>   - Add available values in the binding document
> 
>  Documentation/devicetree/bindings/mtd/denali-nand.txt |  6 ++++++
>  drivers/mtd/nand/denali.c                             | 18 ++++++++++++++++--
>  drivers/mtd/nand/denali_pci.c                         |  1 +
>  3 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/denali-nand.txt b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> index 25313c7..647618e 100644
> --- a/Documentation/devicetree/bindings/mtd/denali-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> @@ -11,6 +11,12 @@ Optional properties:
>    - nand-ecc-step-size: must be 512 or 1024.  If not specified, default to:
>        512   for "altr,socfpga-denali-nand"
>      see nand.txt for details.
> +  - nand-ecc-strength: see nand.txt for details.  Available values are:
> +      8, 15      for "altr,socfpga-denali-nand"
> +  - nand-ecc-maximize: see nand.txt for details
> +
> +Note:
> +Either nand-ecc-strength or nand-ecc-maximize should be specified.
>  
>  The device tree may optionally contain sub-nodes describing partitions of the
>  address space. See partition.txt for more detail.
> diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
> index 96074b8..70e9f06 100644
> --- a/drivers/mtd/nand/denali.c
> +++ b/drivers/mtd/nand/denali.c
> @@ -1627,9 +1627,23 @@ int denali_init(struct denali_nand_info *denali)
>  		goto failed_req_irq;
>  	}
>  
> -	ret = denali_set_max_ecc_strength(denali);
> -	if (ret)
> +	if (!chip->ecc.strength && !(chip->ecc.options & NAND_ECC_MAXIMIZE)) {
> +		dev_info(denali->dev,
> +			 "No ECC strength strategy is specified. Maximizing ECC strength\n");
> +		chip->ecc.options |= NAND_ECC_MAXIMIZE;
> +	}
> +
> +	if (chip->ecc.options & NAND_ECC_MAXIMIZE) {
> +		ret = denali_set_max_ecc_strength(denali);
> +		if (ret)
> +			goto failed_req_irq;
> +	} else if (!(denali->ecc_strength_avail & BIT(chip->ecc.strength))) {
> +		dev_err(denali->dev,
> +			"Specified ECC strength (%d) is not supported for this controller.\n",
> +			chip->ecc.strength);
> +		ret = -EINVAL;
>  		goto failed_req_irq;
> +	}
>  
>  	chip->ecc.bytes = denali_calc_ecc_bytes(chip->ecc.size,
>  						chip->ecc.strength);
> diff --git a/drivers/mtd/nand/denali_pci.c b/drivers/mtd/nand/denali_pci.c
> index a1ee9f8..a39682a5 100644
> --- a/drivers/mtd/nand/denali_pci.c
> +++ b/drivers/mtd/nand/denali_pci.c
> @@ -87,6 +87,7 @@ static int denali_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  
>  	denali->ecc_strength_avail = BIT(15) | BIT(8);
>  	denali->caps |= DENALI_CAP_ECC_SIZE_512;
> +	denali->nand.ecc.options |= NAND_ECC_MAXIMIZE;
>  
>  	ret = denali_init(denali);
>  	if (ret)