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Date: Fri, 1 Apr 2016 09:07:56 -0700
From: Brian Norris <computersforpeace@gmail.com>
To: =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>
Cc: linux-mtd@lists.infradead.org, Hauke Mehrtens <hauke@hauke-m.de>,
 Kamal Dasu <kdasu.kdev@gmail.com>, Rob Herring <robh+dt@kernel.org>,
 Frank Rowand <frowand.list@gmail.com>,
 Grant Likely <grant.likely@linaro.org>, devicetree@vger.kernel.org
Subject: Re: [PATCH 3/3] mtd: brcmnand: fix check for Hamming algorithm
Message-ID: <20160401160756.GD117117@google.com>
References: <1455300685-27009-1-git-send-email-zajec5@gmail.com>
 <1455300685-27009-3-git-send-email-zajec5@gmail.com>
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On Fri, Feb 12, 2016 at 07:11:25PM +0100, Rafał Miłecki wrote:
> So far we were treating ECC strength 1 as Hamming algorithm. It didn't
> supporting some less common devices with BCH-1 (e.g. D-Link DIR-885L).
> 
> Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
> ---
>  drivers/mtd/nand/brcmnand/brcmnand.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
> index 844fc07..b8055da 100644
> --- a/drivers/mtd/nand/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/brcmnand/brcmnand.c
> @@ -1842,7 +1842,7 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>  
>  	switch (chip->ecc.size) {
>  	case 512:
> -		if (chip->ecc.strength == 1) /* Hamming */
> +		if (chip->ecc.algo == NAND_ECC_HAMMING)

It's probably best we do a little more than this. Right now, this allows
someone to specify:

	nand-ecc-strength = <20>;
	nand-ecc-stepsize = <512>;
	nand-ecc-algo = "hamming";
	nand-ecc-mode = "hw";

And they'll end up with 1-bit hamming ECC, except nand_base will still
think we have 20-bit correction. I think we need to add a check in this
driver to be sure we haven't selected >1-bit correction with hamming
ECC.

Brian

>  			cfg->ecc_level = 15;
>  		else
>  			cfg->ecc_level = chip->ecc.strength;
> -- 
> 1.8.4.5
>