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* [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
@ 2018-05-04  2:09 Wan, Jane (Nokia - US/Sunnyvale)
  2018-05-11  5:03 ` Chris Moore
  0 siblings, 1 reply; 2+ messages in thread
From: Wan, Jane (Nokia - US/Sunnyvale) @ 2018-05-04  2:09 UTC (permalink / raw)
  To: Boris Brezillon, Miquel Raynal
  Cc: computersforpeace, Bos, Ties (Nokia - US/Sunnyvale),
	linux-mtd, linux-kernel, richard, marek.vasut, yamada.masahiro,
	prabhakar.kushwaha, shawnguo, jagdish.gediya, shreeya.patel23498

[-- Attachment #1: Type: text/plain, Size: 6088 bytes --]

Hi,

The following is the reposting of patch with v2 version indication based on comment on "[PATCH 1/2]" (also in the attachment).

Subject: [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
 recover the contents of ONFI parameter

Per ONFI specification (Rev. 4.0), if all parameter pages have invalid
CRC values, the bit-wise majority may be used to recover the contents of
the parameter pages from the parameter page copies present.

Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
---
 drivers/mtd/nand/raw/nand_base.c |   36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 72f3a89..464c4fb 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5086,6 +5086,8 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
 	return ret;
 }
 
+#define GET_BIT(bit, val)   (((val) >> (bit)) & 0x01)
+
 /*
  * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
  */
@@ -5094,7 +5096,8 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	struct nand_onfi_params *p;
 	char id[4];
-	int i, ret, val;
+	int i, ret, val, pagesize;
+	u8 *buf;
 
 	/* Try ONFI for unknown chip or LP */
 	ret = nand_readid_op(chip, 0x20, id, sizeof(id));
@@ -5102,8 +5105,9 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 		return 0;
 
 	/* ONFI chip: allocate a buffer to hold its parameter page */
-	p = kzalloc(sizeof(*p), GFP_KERNEL);
-	if (!p)
+	pagesize = sizeof(*p);
+	buf = kzalloc((pagesize * 3), GFP_KERNEL);
+	if (!buf)
 		return -ENOMEM;
 
 	ret = nand_read_param_page_op(chip, 0, NULL, 0);
@@ -5113,7 +5117,8 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	}
 
 	for (i = 0; i < 3; i++) {
-		ret = nand_read_data_op(chip, p, sizeof(*p), true);
+		p = (struct nand_onfi_params *)&buf[i*pagesize];
+		ret = nand_read_data_op(chip, p, pagesize, true);
 		if (ret) {
 			ret = 0;
 			goto free_onfi_param_page;
@@ -5126,8 +5131,27 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	}
 
 	if (i == 3) {
-		pr_err("Could not find valid ONFI parameter page; aborting\n");
-		goto free_onfi_param_page;
+		int j, k, l;
+		u8 v, m;
+
+		pr_err("Could not find valid ONFI parameter page\n");
+		pr_info("Recover ONFI params with bit-wise majority\n");
+		for (j = 0; j < pagesize; j++) {
+			v = 0;
+			for (k = 0; k < 8; k++) {
+				m = 0;
+				for (l = 0; l < 3; l++)
+					m += GET_BIT(k, buf[l*pagesize + j]);
+				if (m > 1)
+					v |= BIT(k);
+			}
+			((u8 *)p)[j] = v;
+		}
+		if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) !=
+				le16_to_cpu(p->crc)) {
+			pr_err("ONFI parameter recovery failed, aborting\n");
+			goto free_onfi_param_page;
+		}
 	}
 
 	/* Check version */
-- 
1.7.9.5

Thanks.
Jane

> -----Original Message-----
> From: Boris Brezillon [mailto:boris.brezillon@bootlin.com]
> Sent: Wednesday, May 02, 2018 3:32 AM
> To: Wan, Jane (Nokia - US/Sunnyvale) <jane.wan@nokia.com>
> Cc: dwmw2@infradead.org; computersforpeace@gmail.com; Bos, Ties (Nokia -
> US/Sunnyvale) <ties.bos@nokia.com>; linux-mtd@lists.infradead.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH 2/2] Use bit-wise majority to recover the contents of ONFI
> parameter
> 
> On Wed, 2 May 2018 12:25:45 +0200
> Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> 
> > Hi Jane,
> >
> > On Thu, 26 Apr 2018 17:19:56 -0700
> > Jane Wan <Jane.Wan@nokia.com> wrote:
> >
> > > Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
> > > ---
> > >  drivers/mtd/nand/nand_base.c |   35 +++++++++++++++++++++++++++++++-
> ---
> > >  1 file changed, 31 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/mtd/nand/nand_base.c
> > > b/drivers/mtd/nand/nand_base.c index c2e1232..161b523 100644
> > > --- a/drivers/mtd/nand/nand_base.c
> > > +++ b/drivers/mtd/nand/nand_base.c
> > > @@ -3153,8 +3153,10 @@ static int nand_flash_detect_onfi(struct
> mtd_info *mtd, struct nand_chip *chip,
> > >  					int *busw)
> > >  {
> > >  	struct nand_onfi_params *p = &chip->onfi_params;
> > > -	int i, j;
> > > -	int val;
> > > +	int i, j, k, len, val;
> > > +	uint8_t copy[3][256], v8;
> > > +
> > > +	len = (sizeof(*p) > 256) ? 256 : sizeof(*p);
> > >
> > >  	/* Try ONFI for unknown chip or LP */
> > >  	chip->cmdfunc(mtd, NAND_CMD_READID, 0x20, -1); @@ -3170,11
> > > +3172,36 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct
> nand_chip *chip,
> > >  				le16_to_cpu(p->crc)) {
> > >  			break;
> > >  		}
> > > +		pr_err("CRC of parameter page %d is not valid\n", i);
> > > +		for (j = 0; j < len; j++)
> > > +			copy[i][j] = ((uint8_t *)p)[j];
> > >  	}
> > >
> > >  	if (i == 3) {
> > > -		pr_err("Could not find valid ONFI parameter page; aborting\n");
> > > -		return 0;
> > > +		pr_err("Could not find valid ONFI parameter page\n");
> > > +		pr_info("Recover ONFI parameters with bit-wise majority\n");
> > > +		for (j = 0; j < len; j++) {
> > > +			if (copy[0][j] == copy[1][j] ||
> > > +			    copy[0][j] == copy[2][j]) {
> > > +				((uint8_t *)p)[j] = copy[0][j];
> > > +			} else if (copy[1][j] == copy[2][j]) {
> > > +				((uint8_t *)p)[j] = copy[1][j];
> > > +			} else {
> > > +				((uint8_t *)p)[j] = 0;
> > > +				for (k = 0; k < 8; k++) {
> > > +					v8 = (copy[0][j] >> k) & 0x1;
> > > +					v8 += (copy[1][j] >> k) & 0x1;
> > > +					v8 += (copy[2][j] >> k) & 0x1;
> > > +					if (v8 > 1)
> > > +						((uint8_t *)p)[j] |= (1 << k);
> > > +				}
> > > +			}
> > > +		}
> >
> > I'd like this bit-wise majority algorithm to be generic and moved to
> > nand_base.c, because we might want to do the same in the core and make
> > it work for any number of repetitions of the PARAM page.
> 
> Never mind, I thought you were implementing that in the FSL IFC driver, but
> you're actually modifying the core.

[-- Attachment #2: 0002-mtd-rawnand-fsl_ifc-use-bit-wise-majority-to-recover.patch --]
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From e14ed7dc08296a52f81d14781dee2f455dd90bbd Mon Sep 17 00:00:00 2001
From: Jane Wan <Jane.Wan@nokia.com>
Date: Mon, 30 Apr 2018 14:05:40 -0700
Subject: [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
 recover the contents of ONFI parameter

Per ONFI specification (Rev. 4.0), if all parameter pages have invalid
CRC values, the bit-wise majority may be used to recover the contents of
the parameter pages from the parameter page copies present.

Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
---
 drivers/mtd/nand/raw/nand_base.c |   36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 72f3a89..464c4fb 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5086,6 +5086,8 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
 	return ret;
 }
 
+#define GET_BIT(bit, val)   (((val) >> (bit)) & 0x01)
+
 /*
  * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
  */
@@ -5094,7 +5096,8 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	struct nand_onfi_params *p;
 	char id[4];
-	int i, ret, val;
+	int i, ret, val, pagesize;
+	u8 *buf;
 
 	/* Try ONFI for unknown chip or LP */
 	ret = nand_readid_op(chip, 0x20, id, sizeof(id));
@@ -5102,8 +5105,9 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 		return 0;
 
 	/* ONFI chip: allocate a buffer to hold its parameter page */
-	p = kzalloc(sizeof(*p), GFP_KERNEL);
-	if (!p)
+	pagesize = sizeof(*p);
+	buf = kzalloc((pagesize * 3), GFP_KERNEL);
+	if (!buf)
 		return -ENOMEM;
 
 	ret = nand_read_param_page_op(chip, 0, NULL, 0);
@@ -5113,7 +5117,8 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	}
 
 	for (i = 0; i < 3; i++) {
-		ret = nand_read_data_op(chip, p, sizeof(*p), true);
+		p = (struct nand_onfi_params *)&buf[i*pagesize];
+		ret = nand_read_data_op(chip, p, pagesize, true);
 		if (ret) {
 			ret = 0;
 			goto free_onfi_param_page;
@@ -5126,8 +5131,27 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
 	}
 
 	if (i == 3) {
-		pr_err("Could not find valid ONFI parameter page; aborting\n");
-		goto free_onfi_param_page;
+		int j, k, l;
+		u8 v, m;
+
+		pr_err("Could not find valid ONFI parameter page\n");
+		pr_info("Recover ONFI params with bit-wise majority\n");
+		for (j = 0; j < pagesize; j++) {
+			v = 0;
+			for (k = 0; k < 8; k++) {
+				m = 0;
+				for (l = 0; l < 3; l++)
+					m += GET_BIT(k, buf[l*pagesize + j]);
+				if (m > 1)
+					v |= BIT(k);
+			}
+			((u8 *)p)[j] = v;
+		}
+		if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) !=
+				le16_to_cpu(p->crc)) {
+			pr_err("ONFI parameter recovery failed, aborting\n");
+			goto free_onfi_param_page;
+		}
 	}
 
 	/* Check version */
-- 
1.7.9.5


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
  2018-05-04  2:09 [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to Wan, Jane (Nokia - US/Sunnyvale)
@ 2018-05-11  5:03 ` Chris Moore
  0 siblings, 0 replies; 2+ messages in thread
From: Chris Moore @ 2018-05-11  5:03 UTC (permalink / raw)
  To: Wan, Jane (Nokia - US/Sunnyvale), Boris Brezillon, Miquel Raynal
  Cc: shreeya.patel23498, yamada.masahiro, richard, linux-kernel,
	marek.vasut, Bos, Ties (Nokia - US/Sunnyvale),
	prabhakar.kushwaha, linux-mtd, jagdish.gediya, computersforpeace,
	shawnguo

Hi,

Le 04/05/2018 à 04:09, Wan, Jane (Nokia - US/Sunnyvale) a écrit
> The following is the reposting of patch with v2 version indication based on comment on "[PATCH 1/2]" (also in the attachment).
>
> Subject: [PATCH v2 2/2] mtd: rawnand: fsl_ifc: use bit-wise majority to
>   recover the contents of ONFI parameter
>
> Per ONFI specification (Rev. 4.0), if all parameter pages have invalid
> CRC values, the bit-wise majority may be used to recover the contents of
> the parameter pages from the parameter page copies present.
>
> Signed-off-by: Jane Wan <Jane.Wan@nokia.com>
> ---
>   drivers/mtd/nand/raw/nand_base.c |   36 ++++++++++++++++++++++++++++++------
>   1 file changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 72f3a89..464c4fb 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c

[snip]

>   
> +		pr_info("Recover ONFI params with bit-wise majority\n");
> +		for (j = 0; j < pagesize; j++) {
> +			v = 0;
> +			for (k = 0; k < 8; k++) {
> +				m = 0;
> +				for (l = 0; l < 3; l++)
> +					m += GET_BIT(k, buf[l*pagesize + j]);
> +				if (m > 1)
> +					v |= BIT(k);
> +			}
> +			((u8 *)p)[j] = v;
> +		}

I am not familiar with the context of this but the three way bit-wise 
majority can be implemented much more efficiently  using the identity:
majority3(a, b, c) = (a & b) | (a & c) | (b & c)
This can be factorized slightly to (a & (b | c)) | (b & c)
This enables the operation to be performed 8, 16, 32 or even 64 bits at 
a time depending on the hardware.

Cheers,
Chris

^ permalink raw reply	[flat|nested] 2+ messages in thread

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