[PATCH] nand_omap_bch_decoder: Fix up error detection

[PATCH] nand_omap_bch_decoder: Fix up error detection

[Teresa Gámez]

From: Steve Schefter <steve@scheftech.com>

Bit errors in the ECC itself are not beeing taken into account.
In this cases the number of detected errors != number of corrected errors and
chien search returns an error.
This patch adds detection of bit errors in the ECC.

Signed-off-by: Steve Schefter <steve@scheftech.com>
Signed-off-by: Teresa Gámez <t.gamez@phytec.de>
---
 drivers/mtd/nand/nand_omap_bch_decoder.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/nand_omap_bch_decoder.c b/drivers/mtd/nand/nand_omap_bch_decoder.c
index 356f71f..d1455e4 100644
--- a/drivers/mtd/nand/nand_omap_bch_decoder.c
+++ b/drivers/mtd/nand/nand_omap_bch_decoder.c
@@ -64,6 +64,7 @@ static int chien(unsigned int select_4_8, int err_nums,
 				unsigned int err[], unsigned int *location)
 {
 	int i, count; /* Number of dectected errors */
+	int errorsinecc; /* Number of detected errors in ECC bits */
 	/* Contains accumulation of evaluation at x^i (i:1->8) */
 	unsigned int gammas[8] = {0};
 	unsigned int alpha;
@@ -77,7 +78,8 @@ static int chien(unsigned int select_4_8, int err_nums,
 		gammas[i] = err[i];
 
 	count = 0;
-	for (i = 1; (i <= nn) && (count < err_nums); i++) {
+	errorsinecc = 0;
+	for (i = 1; (i <= nn) && ((count + errorsinecc) < err_nums); i++) {
 
 		/* Result of evaluation at root */
 		elp_sum = 1 ^ gammas[0] ^ gammas[1] ^
@@ -108,11 +110,13 @@ static int chien(unsigned int select_4_8, int err_nums,
 			if (i >= 2 * ecc_bits)
 				location[count++] =
 					kk_shorten - (bit - 2 * ecc_bits) - 1;
+			else
+				errorsinecc++;
 		}
 	}
 
 	/* Failure: No. of detected errors != No. or corrected errors */
-	if (count != err_nums) {
+	if ((count + errorsinecc) != err_nums) {
 		count = -1;
 		printk(KERN_ERR "BCH decoding failed\n");
 	}
-- 
1.7.0.4


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Re: [PATCH] nand_omap_bch_decoder: Fix up error detection

[Teresa Gamez]

Am Freitag, den 09.12.2011, 11:00 +0100 schrieb Teresa Gámez:
> From: Steve Schefter <steve@scheftech.com>
> 
> Bit errors in the ECC itself are not beeing taken into account.
> In this cases the number of detected errors != number of corrected errors and
> chien search returns an error.
> This patch adds detection of bit errors in the ECC.
> 
> Signed-off-by: Steve Schefter <steve@scheftech.com>
> Signed-off-by: Teresa Gámez <t.gamez@phytec.de>

Ping?

Regards
Teresa

> ---
>  drivers/mtd/nand/nand_omap_bch_decoder.c |    8 ++++++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_omap_bch_decoder.c b/drivers/mtd/nand/nand_omap_bch_decoder.c
> index 356f71f..d1455e4 100644
> --- a/drivers/mtd/nand/nand_omap_bch_decoder.c
> +++ b/drivers/mtd/nand/nand_omap_bch_decoder.c
> @@ -64,6 +64,7 @@ static int chien(unsigned int select_4_8, int err_nums,
>  				unsigned int err[], unsigned int *location)
>  {
>  	int i, count; /* Number of dectected errors */
> +	int errorsinecc; /* Number of detected errors in ECC bits */
>  	/* Contains accumulation of evaluation at x^i (i:1->8) */
>  	unsigned int gammas[8] = {0};
>  	unsigned int alpha;
> @@ -77,7 +78,8 @@ static int chien(unsigned int select_4_8, int err_nums,
>  		gammas[i] = err[i];
>  
>  	count = 0;
> -	for (i = 1; (i <= nn) && (count < err_nums); i++) {
> +	errorsinecc = 0;
> +	for (i = 1; (i <= nn) && ((count + errorsinecc) < err_nums); i++) {
>  
>  		/* Result of evaluation at root */
>  		elp_sum = 1 ^ gammas[0] ^ gammas[1] ^
> @@ -108,11 +110,13 @@ static int chien(unsigned int select_4_8, int err_nums,
>  			if (i >= 2 * ecc_bits)
>  				location[count++] =
>  					kk_shorten - (bit - 2 * ecc_bits) - 1;
> +			else
> +				errorsinecc++;
>  		}
>  	}
>  
>  	/* Failure: No. of detected errors != No. or corrected errors */
> -	if (count != err_nums) {
> +	if ((count + errorsinecc) != err_nums) {
>  		count = -1;
>  		printk(KERN_ERR "BCH decoding failed\n");
>  	}


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Re: [PATCH] nand_omap_bch_decoder: Fix up error detection

[Sascha Hauer]

On Wed, Dec 21, 2011 at 02:18:38PM +0100, Teresa Gamez wrote:
> Am Freitag, den 09.12.2011, 11:00 +0100 schrieb Teresa Gámez:
> > From: Steve Schefter <steve@scheftech.com>
> > 
> > Bit errors in the ECC itself are not beeing taken into account.
> > In this cases the number of detected errors != number of corrected errors and
> > chien search returns an error.
> > This patch adds detection of bit errors in the ECC.
> > 
> > Signed-off-by: Steve Schefter <steve@scheftech.com>
> > Signed-off-by: Teresa Gámez <t.gamez@phytec.de>
> 
> Ping?

Applied now.

Sascha


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