[U-Boot,v2,8/8] nand: make 1-bit software ECC configurable
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Message ID 1318404726-27147-8-git-send-email-christian.hitz@aizo.com
State Accepted
Commit 4fee6c2f295f932b8febdc7ce8731ba045695fa5
Delegated to: Scott Wood
Headers show

Commit Message

Christian Hitz Oct. 12, 2011, 7:32 a.m. UTC
The software ECC algorithm is not necessary when hardware ECC
is available and can be left out for a smaller image size.
Enable with CONFIG_MTD_ECC_SOFT.

Signed-off-by: Christian Hitz <christian.hitz@aizo.com>
Cc: Scott Wood <scottwood@freescale.com>
---

Saves 2312 bytes of image size when software ECC is not used.

Changes since v1:
	- new option to disable software ECC

 drivers/mtd/nand/Makefile    |    2 +-
 drivers/mtd/nand/nand_base.c |    4 ++++
 include/linux/mtd/nand_ecc.h |   25 +++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletions(-)

Comments

Scott Wood Nov. 1, 2011, 10:04 p.m. UTC | #1
On Wed, Oct 12, 2011 at 09:32:06AM +0200, Christian Hitz wrote:
> The software ECC algorithm is not necessary when hardware ECC
> is available and can be left out for a smaller image size.
> Enable with CONFIG_MTD_ECC_SOFT.
> 
> Signed-off-by: Christian Hitz <christian.hitz@aizo.com>
> Cc: Scott Wood <scottwood@freescale.com>
> ---
> 
> Saves 2312 bytes of image size when software ECC is not used.
> 
> Changes since v1:
> 	- new option to disable software ECC
> 
>  drivers/mtd/nand/Makefile    |    2 +-
>  drivers/mtd/nand/nand_base.c |    4 ++++
>  include/linux/mtd/nand_ecc.h |   25 +++++++++++++++++++++++++
>  3 files changed, 30 insertions(+), 1 deletions(-)

Please check which boards select drivers which may use soft ECC,
and have them #define CONFIG_MTD_ECC_SOFT.

-Scott
Scott Wood Nov. 1, 2011, 10:08 p.m. UTC | #2
On 11/01/2011 05:04 PM, Scott Wood wrote:
> On Wed, Oct 12, 2011 at 09:32:06AM +0200, Christian Hitz wrote:
>> The software ECC algorithm is not necessary when hardware ECC
>> is available and can be left out for a smaller image size.
>> Enable with CONFIG_MTD_ECC_SOFT.
>>
>> Signed-off-by: Christian Hitz <christian.hitz@aizo.com>
>> Cc: Scott Wood <scottwood@freescale.com>
>> ---
>>
>> Saves 2312 bytes of image size when software ECC is not used.
>>
>> Changes since v1:
>> 	- new option to disable software ECC
>>
>>  drivers/mtd/nand/Makefile    |    2 +-
>>  drivers/mtd/nand/nand_base.c |    4 ++++
>>  include/linux/mtd/nand_ecc.h |   25 +++++++++++++++++++++++++
>>  3 files changed, 30 insertions(+), 1 deletions(-)
> 
> Please check which boards select drivers which may use soft ECC,
> and have them #define CONFIG_MTD_ECC_SOFT.

Also document the option in doc/README.nand, and it should probably be
CONFIG_SYS_NAND_ECC_SOFT.

-Scott
Scott Wood Nov. 1, 2011, 10:09 p.m. UTC | #3
On 11/01/2011 05:08 PM, Scott Wood wrote:
> On 11/01/2011 05:04 PM, Scott Wood wrote:
>> On Wed, Oct 12, 2011 at 09:32:06AM +0200, Christian Hitz wrote:
>>> The software ECC algorithm is not necessary when hardware ECC
>>> is available and can be left out for a smaller image size.
>>> Enable with CONFIG_MTD_ECC_SOFT.
>>>
>>> Signed-off-by: Christian Hitz <christian.hitz@aizo.com>
>>> Cc: Scott Wood <scottwood@freescale.com>
>>> ---
>>>
>>> Saves 2312 bytes of image size when software ECC is not used.
>>>
>>> Changes since v1:
>>> 	- new option to disable software ECC
>>>
>>>  drivers/mtd/nand/Makefile    |    2 +-
>>>  drivers/mtd/nand/nand_base.c |    4 ++++
>>>  include/linux/mtd/nand_ecc.h |   25 +++++++++++++++++++++++++
>>>  3 files changed, 30 insertions(+), 1 deletions(-)
>>
>> Please check which boards select drivers which may use soft ECC,
>> and have them #define CONFIG_MTD_ECC_SOFT.
> 
> Also document the option in doc/README.nand, and it should probably be
> CONFIG_SYS_NAND_ECC_SOFT.

Ignore me on the CONFIG_SYS bit, not sure what I was thinking.

-Scott

Patch
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diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index 3781cc1..e9e2f80 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -36,7 +36,7 @@  COBJS-y += nand_bbt.o
 COBJS-y += nand_ids.o
 COBJS-y += nand_util.o
 endif
-COBJS-y += nand_ecc.o
+COBJS-$(CONFIG_MTD_ECC_SOFT) += nand_ecc.o
 COBJS-y += nand_base.o
 COBJS-$(CONFIG_NAND_ECC_BCH) += nand_bch.o
 
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 26c3847..ba6db02 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3035,6 +3035,10 @@  int nand_scan_tail(struct mtd_info *mtd)
 		chip->ecc.mode = NAND_ECC_SOFT;
 
 	case NAND_ECC_SOFT:
+		if (!mtd_nand_has_ecc_soft()) {
+			printk(KERN_WARNING "CONFIG_MTD_ECC_SOFT not enabled\n");
+			return -EINVAL;
+		}
 		chip->ecc.calculate = nand_calculate_ecc;
 		chip->ecc.correct = nand_correct_data;
 		chip->ecc.read_page = nand_read_page_swecc;
diff --git a/include/linux/mtd/nand_ecc.h b/include/linux/mtd/nand_ecc.h
index 090da50..9715a53 100644
--- a/include/linux/mtd/nand_ecc.h
+++ b/include/linux/mtd/nand_ecc.h
@@ -15,6 +15,10 @@ 
 
 struct mtd_info;
 
+#if defined(CONFIG_MTD_ECC_SOFT)
+
+static inline int mtd_nand_has_ecc_soft(void) { return 1; }
+
 /*
  * Calculate 3 byte ECC code for 256 byte block
  */
@@ -25,4 +29,25 @@  int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code
  */
 int nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc);
 
+#else
+
+static inline int mtd_nand_has_ecc_soft(void) { return 0; }
+
+static inline int
+nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code)
+{
+	return -1;
+}
+
+static inline int
+nand_correct_data(struct mtd_info *mtd,
+			u_char *dat,
+			u_char *read_ecc,
+			u_char *calc_ecc)
+{
+	return -1;
+}
+
+#endif
+
 #endif /* __MTD_NAND_ECC_H__ */