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mtd: nand: mxs: Calculate ECC strength dynamically

PATCH New Jörg Krause 2 participants 6 messages Apr 15, 2015 – Apr 16, 2015

Subsystems (3)
Arm i.MX and Layerscape Memory technology devices (MTD) NAND flash
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Jörg Krause

author
#0 lore raw

v3 cover mtd: nand: mxs: Calculate ECC strength dynamically

This patchset is based on the patch from Peng Fan:
"[U-Boot,1/2] mtd:mxs:nand calculate ecc strength dynamically"
https://patchwork.ozlabs.org/patch/422756/

Instead of hard-coding every possible oob size / ECC strength combination calculate the ECC strength dynamically to be aligned with the Linux Kernel MTD NAND driver. Also adds the calculation to tools/mxsboot to be aligned with the U-Boot MTD NAND driver.

J?rg Krause (2):
mtd: nand: mxs: Replace magic number for bits per ECC level with macro
tools: mxsboot: Calculate ECC strength dynamically

Peng Fan (1):
mtd:mxs:nand calculate ecc strength dynamically

 drivers/mtd/nand/mxs_nand.c | 35 +++++++++++++++--------------------
 tools/mxsboot.c             | 39 ++++++++++++++++++++++++---------------
 2 files changed, 39 insertions(+), 35 deletions(-)
Signature · 1 line
2.3.5
author
#1 lore raw

PATCH v3 1/3 mtd:mxs:nand calculate ecc strength dynamically

From: Peng Fan <[email protected]>

Calculate ecc strength according oobsize, but not hardcoded which is not aligned with kernel driver

Signed-off-by Peng Fan <[email protected]>
Signed-off-by Ye.Li <[email protected]>
Reviewed-by Marek Vasut <[email protected]>
Signed-off-by J?rg Krause <[email protected]>

---
Changes for v3:
- squashed "[U-Boot,v2,3/4] mtd: nand: mxs: Add comment for calculating

     ECC strength"
     https://patchwork.ozlabs.org/patch/460926/
   - Coding Style cleanup
Changes for v2:
   - None (original patch from Peng Fan)
---
 drivers/mtd/nand/mxs_nand.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)
drivers/mtd/nand/mxs_nand.c +12 -18
index 7a064ab..a463de7 100644
@@ -146,26 +146,20 @@ static uint32_t mxs_nand_aux_status_offset(void)
 static inline uint32_t mxs_nand_get_ecc_strength(uint32_t page_data_size,
 						uint32_t page_oob_size)
 {
-	if (page_data_size == 2048) {
-		if (page_oob_size == 64)
-			return 8;
+	int ecc_strength;
 
-		if (page_oob_size == 112)
-			return 14;
-	}
-
-	if (page_data_size == 4096) {
-		if (page_oob_size == 128)
-			return 8;
-
-		if (page_oob_size == 218)
-			return 16;
-
-		if (page_oob_size == 224)
-			return 16;
-	}
+	/*
+	 * Determine the ECC layout with the formula:
+	 *	ECC bits per chunk = (total page spare data bits) /
+	 *		(bits per ECC level) / (chunks per page)
+	 * where:
+	 *	total page spare data bits =
+	 *		(page oob size - meta data size) * (bits per byte)
+	 */
+	ecc_strength = ((page_oob_size - MXS_NAND_METADATA_SIZE) * 8)
+			/ (13 * mxs_nand_ecc_chunk_cnt(page_data_size));
 
-	return 0;
+	return round_down(ecc_strength, 2);
 }
 
 static inline uint32_t mxs_nand_get_mark_offset(uint32_t page_data_size,
Signature · 1 line
2.3.5
author
#2 lore raw

PATCH v3 2/3 mtd: nand: mxs: Replace magic number for bits per ECC level with macro

In reply to Jörg Krause
Signed-off-by J?rg Krause <[email protected]>

---
Changes for v3:
- Replace space with tab for macro definition
Changes for v2:
- New patch

---
 drivers/mtd/nand/mxs_nand.c | 7 ++++---
 tools/mxsboot.c             | 3 ++-
 2 files changed, 6 insertions(+), 4 deletions(-)
drivers/mtd/nand/mxs_nand.c +4 -3
index a463de7..aa06446 100644
@@ -36,7 +36,7 @@
 #define	MXS_NAND_CHUNK_DATA_CHUNK_SIZE_SHIFT	0
 #endif
 #define	MXS_NAND_METADATA_SIZE			10
-
+#define	MXS_NAND_BITS_PER_ECC_LEVEL		13
 #define	MXS_NAND_COMMAND_BUFFER_SIZE		32
 
 #define	MXS_NAND_BCH_TIMEOUT			10000

@@ -135,7 +135,7 @@ static uint32_t mxs_nand_ecc_chunk_cnt(uint32_t page_data_size)
 
 static uint32_t mxs_nand_ecc_size_in_bits(uint32_t ecc_strength)
 {
-	return ecc_strength * 13;
+	return ecc_strength * MXS_NAND_BITS_PER_ECC_LEVEL;
 }
 
 static uint32_t mxs_nand_aux_status_offset(void)

@@ -157,7 +157,8 @@ static inline uint32_t mxs_nand_get_ecc_strength(uint32_t page_data_size,
 	 *		(page oob size - meta data size) * (bits per byte)
 	 */
 	ecc_strength = ((page_oob_size - MXS_NAND_METADATA_SIZE) * 8)
-			/ (13 * mxs_nand_ecc_chunk_cnt(page_data_size));
+			/ (MXS_NAND_BITS_PER_ECC_LEVEL *
+				mxs_nand_ecc_chunk_cnt(page_data_size));
 
 	return round_down(ecc_strength, 2);
 }
tools/mxsboot.c +2 -1
index 6d48cfb..aaa872b 100644
@@ -48,6 +48,7 @@ static uint32_t sd_sector = 2048;
 #define	MXS_NAND_DMA_DESCRIPTOR_COUNT		4
 #define	MXS_NAND_CHUNK_DATA_CHUNK_SIZE		512
 #define	MXS_NAND_METADATA_SIZE			10
+#define	MXS_NAND_BITS_PER_ECC_LEVEL		13
 #define	MXS_NAND_COMMAND_BUFFER_SIZE		32
 
 struct mx28_nand_fcb {

@@ -127,7 +128,7 @@ struct mx28_sd_config_block {
 
 static inline uint32_t mx28_nand_ecc_size_in_bits(uint32_t ecc_strength)
 {
-	return ecc_strength * 13;
+	return ecc_strength * MXS_NAND_BITS_PER_ECC_LEVEL;
 }
 
 static inline uint32_t mx28_nand_get_ecc_strength(uint32_t page_data_size,
Signature · 1 line
2.3.5
author
#4 lore raw

PATCH v3 3/3 tools: mxsboot: Calculate ECC strength dynamically

In reply to Jörg Krause

Calculating the ECC strength dynamically to be aligned with the mxs NAND driver and the Linux Kernel.

Signed-off-by J?rg Krause <[email protected]>

---
Changes for v3:
- Coding Style cleanup
Changes for v2:
- New patch

---
 tools/mxsboot.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)
tools/mxsboot.c +22 -13
index aaa872b..53de452 100644
@@ -14,6 +14,10 @@
 
 #include "compiler.h"
 
+/* Taken from <linux/kernel.h> */
+#define __round_mask(x, y) ((__typeof__(x))((y)-1))
+#define round_down(x, y) ((x) & ~__round_mask(x, y))
+
 /*
  * Default BCB layout.
  *

@@ -126,6 +130,11 @@ struct mx28_sd_config_block {
 	struct mx28_sd_drive_info	drv_info[1];
 };
 
+static inline uint32_t mx28_nand_ecc_chunk_cnt(uint32_t page_data_size)
+{
+	return page_data_size / MXS_NAND_CHUNK_DATA_CHUNK_SIZE;
+}
+
 static inline uint32_t mx28_nand_ecc_size_in_bits(uint32_t ecc_strength)
 {
 	return ecc_strength * MXS_NAND_BITS_PER_ECC_LEVEL;

@@ -134,21 +143,21 @@ static inline uint32_t mx28_nand_ecc_size_in_bits(uint32_t ecc_strength)
 static inline uint32_t mx28_nand_get_ecc_strength(uint32_t page_data_size,
 						uint32_t page_oob_size)
 {
-	if (page_data_size == 2048)
-		return 8;
-
-	if (page_data_size == 4096) {
-		if (page_oob_size == 128)
-			return 8;
+	int ecc_strength;
 
-		if (page_oob_size == 218)
-			return 16;
-
-		if (page_oob_size == 224)
-			return 16;
-	}
+	/*
+	 * Determine the ECC layout with the formula:
+	 *	ECC bits per chunk = (total page spare data bits) /
+	 *		(bits per ECC level) / (chunks per page)
+	 * where:
+	 *	total page spare data bits =
+	 *		(page oob size - meta data size) * (bits per byte)
+	 */
+	ecc_strength = ((page_oob_size - MXS_NAND_METADATA_SIZE) * 8)
+			/ (MXS_NAND_BITS_PER_ECC_LEVEL *
+				mx28_nand_ecc_chunk_cnt(page_data_size));
 
-	return 0;
+	return round_down(ecc_strength, 2);
 }
 
 static inline uint32_t mx28_nand_get_mark_offset(uint32_t page_data_size,
Signature · 1 line
2.3.5