[PATCH v2 1/5] mtd: rawnand/davinci: Don't calculate ECC when reading page

[PATCH v2 1/5] mtd: rawnand/davinci: Don't calculate ECC when reading page

[Paul Cercueil]

The function nand_davinci_read_page_hwecc_oob_first() does read the ECC
data from the OOB area. Therefore it does not need to calculate the ECC
as it is already available.

Cc: <stable@vger.kernel.org> # v5.2
Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/mtd/nand/raw/davinci_nand.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/davinci_nand.c b/drivers/mtd/nand/raw/davinci_nand.c
index 118da9944e3b..89de24d3bb7a 100644
--- a/drivers/mtd/nand/raw/davinci_nand.c
+++ b/drivers/mtd/nand/raw/davinci_nand.c
@@ -394,7 +394,6 @@ static int nand_davinci_read_page_hwecc_oob_first(struct nand_chip *chip,
 	int eccsteps = chip->ecc.steps;
 	uint8_t *p = buf;
 	uint8_t *ecc_code = chip->ecc.code_buf;
-	uint8_t *ecc_calc = chip->ecc.calc_buf;
 	unsigned int max_bitflips = 0;
 
 	/* Read the OOB area first */
@@ -420,8 +419,6 @@ static int nand_davinci_read_page_hwecc_oob_first(struct nand_chip *chip,
 		if (ret)
 			return ret;
 
-		chip->ecc.calculate(chip, p, &ecc_calc[i]);
-
 		stat = chip->ecc.correct(chip, p, &ecc_code[i], NULL);
 		if (stat == -EBADMSG &&
 		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
-- 
2.33.0

[PATCH v2 2/5] mtd: rawnand/davinci: Avoid duplicated page read

[Paul Cercueil]

The function nand_davinci_read_page_hwecc_oob_first() first reads the
OOB data, extracts the ECC information, programs the ECC hardware before
reading the actual data in a loop.

Right after the OOB data was read, it called nand_read_page_op() to
reset the read cursor to the beginning of the page. This caused the
first page to be read twice: in that call, and later in the loop.

Address that issue by changing the call to nand_read_page_op() to
nand_change_read_column_op(), which will only reset the read cursor.

Cc: <stable@vger.kernel.org> # v5.2
Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/mtd/nand/raw/davinci_nand.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/davinci_nand.c b/drivers/mtd/nand/raw/davinci_nand.c
index 89de24d3bb7a..2e6a0c1671be 100644
--- a/drivers/mtd/nand/raw/davinci_nand.c
+++ b/drivers/mtd/nand/raw/davinci_nand.c
@@ -401,7 +401,8 @@ static int nand_davinci_read_page_hwecc_oob_first(struct nand_chip *chip,
 	if (ret)
 		return ret;
 
-	ret = nand_read_page_op(chip, page, 0, NULL, 0);
+	/* Move read cursor to start of page */
+	ret = nand_change_read_column_op(chip, 0, NULL, 0, false);
 	if (ret)
 		return ret;
 
-- 
2.33.0

[PATCH v2 3/5] mtd: rawnand/davinci: Rewrite function description

[Paul Cercueil]

The original comment that describes the function
nand_davinci_read_page_hwecc_oob_first() is very obscure and it is hard
to understand what it is for.

Cc: <stable@vger.kernel.org> # v5.2
Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/mtd/nand/raw/davinci_nand.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/davinci_nand.c b/drivers/mtd/nand/raw/davinci_nand.c
index 2e6a0c1671be..fe2511cdcae3 100644
--- a/drivers/mtd/nand/raw/davinci_nand.c
+++ b/drivers/mtd/nand/raw/davinci_nand.c
@@ -372,17 +372,15 @@ static int nand_davinci_correct_4bit(struct nand_chip *chip, u_char *data,
 }
 
 /**
- * nand_read_page_hwecc_oob_first - hw ecc, read oob first
+ * nand_davinci_read_page_hwecc_oob_first - Hardware ECC page read with ECC
+ *                                          data read from OOB area
  * @chip: nand chip info structure
  * @buf: buffer to store read data
  * @oob_required: caller requires OOB data read to chip->oob_poi
  * @page: page number to read
  *
- * Hardware ECC for large page chips, require OOB to be read first. For this
- * ECC mode, the write_page method is re-used from ECC_HW. These methods
- * read/write ECC from the OOB area, unlike the ECC_HW_SYNDROME support with
- * multiple ECC steps, follows the "infix ECC" scheme and reads/writes ECC from
- * the data area, by overwriting the NAND manufacturer bad block markings.
+ * Hardware ECC for large page chips, which requires the ECC data to be
+ * extracted from the OOB before the actual data is read.
  */
 static int nand_davinci_read_page_hwecc_oob_first(struct nand_chip *chip,
 						  uint8_t *buf,
-- 
2.33.0

[PATCH v2 4/5] mtd: rawnand: Export nand_read_page_hwecc_oob_first()

[Paul Cercueil]

Move the function nand_read_page_hwecc_oob_first() (previously
nand_davinci_read_page_hwecc_oob_first()) to nand_base.c, and export it
as a GPL symbol, so that it can be used by more modules.

Cc: <stable@vger.kernel.org> # v5.2
Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/mtd/nand/raw/davinci_nand.c | 69 +----------------------------
 drivers/mtd/nand/raw/nand_base.c    | 67 ++++++++++++++++++++++++++++
 include/linux/mtd/rawnand.h         |  2 +
 3 files changed, 70 insertions(+), 68 deletions(-)

diff --git a/drivers/mtd/nand/raw/davinci_nand.c b/drivers/mtd/nand/raw/davinci_nand.c
index fe2511cdcae3..45fec8c192ab 100644
--- a/drivers/mtd/nand/raw/davinci_nand.c
+++ b/drivers/mtd/nand/raw/davinci_nand.c
@@ -371,73 +371,6 @@ static int nand_davinci_correct_4bit(struct nand_chip *chip, u_char *data,
 	return corrected;
 }
 
-/**
- * nand_davinci_read_page_hwecc_oob_first - Hardware ECC page read with ECC
- *                                          data read from OOB area
- * @chip: nand chip info structure
- * @buf: buffer to store read data
- * @oob_required: caller requires OOB data read to chip->oob_poi
- * @page: page number to read
- *
- * Hardware ECC for large page chips, which requires the ECC data to be
- * extracted from the OOB before the actual data is read.
- */
-static int nand_davinci_read_page_hwecc_oob_first(struct nand_chip *chip,
-						  uint8_t *buf,
-						  int oob_required, int page)
-{
-	struct mtd_info *mtd = nand_to_mtd(chip);
-	int i, eccsize = chip->ecc.size, ret;
-	int eccbytes = chip->ecc.bytes;
-	int eccsteps = chip->ecc.steps;
-	uint8_t *p = buf;
-	uint8_t *ecc_code = chip->ecc.code_buf;
-	unsigned int max_bitflips = 0;
-
-	/* Read the OOB area first */
-	ret = nand_read_oob_op(chip, page, 0, chip->oob_poi, mtd->oobsize);
-	if (ret)
-		return ret;
-
-	/* Move read cursor to start of page */
-	ret = nand_change_read_column_op(chip, 0, NULL, 0, false);
-	if (ret)
-		return ret;
-
-	ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
-					 chip->ecc.total);
-	if (ret)
-		return ret;
-
-	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
-		int stat;
-
-		chip->ecc.hwctl(chip, NAND_ECC_READ);
-
-		ret = nand_read_data_op(chip, p, eccsize, false, false);
-		if (ret)
-			return ret;
-
-		stat = chip->ecc.correct(chip, p, &ecc_code[i], NULL);
-		if (stat == -EBADMSG &&
-		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
-			/* check for empty pages with bitflips */
-			stat = nand_check_erased_ecc_chunk(p, eccsize,
-							   &ecc_code[i],
-							   eccbytes, NULL, 0,
-							   chip->ecc.strength);
-		}
-
-		if (stat < 0) {
-			mtd->ecc_stats.failed++;
-		} else {
-			mtd->ecc_stats.corrected += stat;
-			max_bitflips = max_t(unsigned int, max_bitflips, stat);
-		}
-	}
-	return max_bitflips;
-}
-
 /*----------------------------------------------------------------------*/
 
 /* An ECC layout for using 4-bit ECC with small-page flash, storing
@@ -647,7 +580,7 @@ static int davinci_nand_attach_chip(struct nand_chip *chip)
 			} else if (chunks == 4 || chunks == 8) {
 				mtd_set_ooblayout(mtd,
 						  nand_get_large_page_ooblayout());
-				chip->ecc.read_page = nand_davinci_read_page_hwecc_oob_first;
+				chip->ecc.read_page = nand_read_page_hwecc_oob_first;
 			} else {
 				return -EIO;
 			}
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 3d6c6e880520..113a2e9f43b1 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -3160,6 +3160,73 @@ static int nand_read_page_hwecc(struct nand_chip *chip, uint8_t *buf,
 	return max_bitflips;
 }
 
+/**
+ * nand_read_page_hwecc_oob_first - Hardware ECC page read with ECC
+ *                                  data read from OOB area
+ * @chip: nand chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * Hardware ECC for large page chips, which requires the ECC data to be
+ * extracted from the OOB before the actual data is read.
+ */
+int nand_read_page_hwecc_oob_first(struct nand_chip *chip, uint8_t *buf,
+				   int oob_required, int page)
+{
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	int i, eccsize = chip->ecc.size, ret;
+	int eccbytes = chip->ecc.bytes;
+	int eccsteps = chip->ecc.steps;
+	uint8_t *p = buf;
+	uint8_t *ecc_code = chip->ecc.code_buf;
+	unsigned int max_bitflips = 0;
+
+	/* Read the OOB area first */
+	ret = nand_read_oob_op(chip, page, 0, chip->oob_poi, mtd->oobsize);
+	if (ret)
+		return ret;
+
+	/* Move read cursor to start of page */
+	ret = nand_change_read_column_op(chip, 0, NULL, 0, false);
+	if (ret)
+		return ret;
+
+	ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
+					 chip->ecc.total);
+	if (ret)
+		return ret;
+
+	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
+		int stat;
+
+		chip->ecc.hwctl(chip, NAND_ECC_READ);
+
+		ret = nand_read_data_op(chip, p, eccsize, false, false);
+		if (ret)
+			return ret;
+
+		stat = chip->ecc.correct(chip, p, &ecc_code[i], NULL);
+		if (stat == -EBADMSG &&
+		    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
+			/* check for empty pages with bitflips */
+			stat = nand_check_erased_ecc_chunk(p, eccsize,
+							   &ecc_code[i],
+							   eccbytes, NULL, 0,
+							   chip->ecc.strength);
+		}
+
+		if (stat < 0) {
+			mtd->ecc_stats.failed++;
+		} else {
+			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
+	}
+	return max_bitflips;
+}
+EXPORT_SYMBOL_GPL(nand_read_page_hwecc_oob_first);
+
 /**
  * nand_read_page_syndrome - [REPLACEABLE] hardware ECC syndrome based page read
  * @chip: nand chip info structure
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index b2f9dd3cbd69..5b88cd51fadb 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1539,6 +1539,8 @@ int nand_read_data_op(struct nand_chip *chip, void *buf, unsigned int len,
 		      bool force_8bit, bool check_only);
 int nand_write_data_op(struct nand_chip *chip, const void *buf,
 		       unsigned int len, bool force_8bit);
+int nand_read_page_hwecc_oob_first(struct nand_chip *chip, uint8_t *buf,
+				   int oob_required, int page);
 
 /* Scan and identify a NAND device */
 int nand_scan_with_ids(struct nand_chip *chip, unsigned int max_chips,
-- 
2.33.0

[PATCH v2 5/5] mtd: rawnand/ingenic: JZ4740 needs 'oob_first' read page function

[Paul Cercueil]

The ECC engine on the JZ4740 SoC requires the ECC data to be read before
the page; using the default page reading function does not work. Indeed,
the old JZ4740 NAND driver (removed in 5.4) did use the 'OOB first' flag
that existed back then.

Use the newly created nand_read_page_hwecc_oob_first() to address this
issue.

This issue was not found when the new ingenic-nand driver was developed,
most likely because the Device Tree used had the nand-ecc-mode set to
"hw_oob_first", which seems to not be supported anymore.

Cc: <stable@vger.kernel.org> # v5.2
Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c b/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
index 0e9d426fe4f2..b18861bdcdc8 100644
--- a/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
+++ b/drivers/mtd/nand/raw/ingenic/ingenic_nand_drv.c
@@ -32,6 +32,7 @@ struct jz_soc_info {
 	unsigned long addr_offset;
 	unsigned long cmd_offset;
 	const struct mtd_ooblayout_ops *oob_layout;
+	bool oob_first;
 };
 
 struct ingenic_nand_cs {
@@ -240,6 +241,9 @@ static int ingenic_nand_attach_chip(struct nand_chip *chip)
 	if (chip->bbt_options & NAND_BBT_USE_FLASH)
 		chip->bbt_options |= NAND_BBT_NO_OOB;
 
+	if (nfc->soc_info->oob_first)
+		chip->ecc.read_page = nand_read_page_hwecc_oob_first;
+
 	/* For legacy reasons we use a different layout on the qi,lb60 board. */
 	if (of_machine_is_compatible("qi,lb60"))
 		mtd_set_ooblayout(mtd, &qi_lb60_ooblayout_ops);
@@ -534,6 +538,7 @@ static const struct jz_soc_info jz4740_soc_info = {
 	.data_offset = 0x00000000,
 	.cmd_offset = 0x00008000,
 	.addr_offset = 0x00010000,
+	.oob_first = true,
 };
 
 static const struct jz_soc_info jz4725b_soc_info = {
-- 
2.33.0

Re: [PATCH v2 5/5] mtd: rawnand/ingenic: JZ4740 needs 'oob_first' read page function

[Miquel Raynal]

On Sat, 2021-10-16 at 13:22:28 UTC, Paul Cercueil wrote:
> The ECC engine on the JZ4740 SoC requires the ECC data to be read before
> the page; using the default page reading function does not work. Indeed,
> the old JZ4740 NAND driver (removed in 5.4) did use the 'OOB first' flag
> that existed back then.
> 
> Use the newly created nand_read_page_hwecc_oob_first() to address this
> issue.
> 
> This issue was not found when the new ingenic-nand driver was developed,
> most likely because the Device Tree used had the nand-ecc-mode set to
> "hw_oob_first", which seems to not be supported anymore.
> 
> Cc: <stable@vger.kernel.org> # v5.2
> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

Re: [PATCH v2 4/5] mtd: rawnand: Export nand_read_page_hwecc_oob_first()

[Miquel Raynal]

On Sat, 2021-10-16 at 13:22:27 UTC, Paul Cercueil wrote:
> Move the function nand_read_page_hwecc_oob_first() (previously
> nand_davinci_read_page_hwecc_oob_first()) to nand_base.c, and export it
> as a GPL symbol, so that it can be used by more modules.
> 
> Cc: <stable@vger.kernel.org> # v5.2
> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

Re: [PATCH v2 3/5] mtd: rawnand/davinci: Rewrite function description

[Miquel Raynal]

On Sat, 2021-10-16 at 13:22:26 UTC, Paul Cercueil wrote:
> The original comment that describes the function
> nand_davinci_read_page_hwecc_oob_first() is very obscure and it is hard
> to understand what it is for.
> 
> Cc: <stable@vger.kernel.org> # v5.2
> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

Re: [PATCH v2 2/5] mtd: rawnand/davinci: Avoid duplicated page read

[Miquel Raynal]

On Sat, 2021-10-16 at 13:22:25 UTC, Paul Cercueil wrote:
> The function nand_davinci_read_page_hwecc_oob_first() first reads the
> OOB data, extracts the ECC information, programs the ECC hardware before
> reading the actual data in a loop.
> 
> Right after the OOB data was read, it called nand_read_page_op() to
> reset the read cursor to the beginning of the page. This caused the
> first page to be read twice: in that call, and later in the loop.
> 
> Address that issue by changing the call to nand_read_page_op() to
> nand_change_read_column_op(), which will only reset the read cursor.
> 
> Cc: <stable@vger.kernel.org> # v5.2
> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

Re: [PATCH v2 1/5] mtd: rawnand/davinci: Don't calculate ECC when reading page

[Miquel Raynal]

On Sat, 2021-10-16 at 13:22:24 UTC, Paul Cercueil wrote:
> The function nand_davinci_read_page_hwecc_oob_first() does read the ECC
> data from the OOB area. Therefore it does not need to calculate the ECC
> as it is already available.
> 
> Cc: <stable@vger.kernel.org> # v5.2
> Fixes: a0ac778eb82c ("mtd: rawnand: ingenic: Add support for the JZ4740")
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel