mtd: nand: omap: add CONFIG_NAND_OMAP_ECCSCHEME for selection of ecc-scheme

Quoted 1 line

Quoted 1 line

"Gupta, Pekon" <[email protected]> schrieb am 21.11.13 um 06:12:

This patch adds new CONFIG_NAND_OMAP_ECCSCHEME, replacing other

CONFIG_xx used for selecting NAND ecc-schemes.
This patch aims at solving following issues.

1) Currently ecc-scheme is tied to SoC platform, which prevents user

select
other ecc-schemes also supported in hardware. like;
- most of OMAP3 SoC platforms use only 1-bit Hamming ecc-scheme,

the fact that they can use higher ecc-schemes like 8-bit

software based error detection

- most of AM33xx SoC plaforms use 8-bit BCH ecc-scheme for now, but

supports BCH16 ecc-scheme also.

2) Different platforms use different CONFIG_xx to select ecc-schemes,

adds confusion for user while migrating platforms.
- *CONFIG_NAND_OMAP_ELM* which enables ELM hardware engine, selects

8-bit BCH ecc-scheme with h/w based error-correction
(OMAP_ECC_BCH8_CODE_HW)

    whereas ELM hardware engine supports other ecc-schemes also like;

and BCH16 (in future).
- *CONFIG_NAND_OMAP_BCH8* selects 8-bit BCH ecc-scheme with s/w

correction (OMAP_ECC_BCH8_CODE_HW_DETECTION_SW).
- *CONFIG_SPL_NAND_SOFTECC* selects 1-bit Hamming ecc-scheme using

Thus adding new *CONFIG_NAND_OMAP_ECCSCHEME* de-couples ecc-scheme

on SoC platform and NAND driver. And user can select ecc-scheme

foreach board.
However, selection some hardware based ecc-schemes

still
depends on presence of ELM hardware engine on SoC. (Refer

Signed-off-by Pekon Gupta <[email protected]>

---
 doc/README.nand                        | 23 +++++++++++++++++++++++
 doc/README.omap3                       |  3 +--
 drivers/mtd/nand/omap_gpmc.c           | 13 ++++---------
 include/configs/am335x_evm.h           |  3 ++-
 include/configs/am335x_igep0033.h      |  1 +
 include/configs/am3517_crane.h         |  1 +
 include/configs/am3517_evm.h           |  1 +
 include/configs/devkit8000.h           |  1 +
 include/configs/mcx.h                  |  2 +-
 include/configs/omap3_beagle.h         |  1 +
 include/configs/omap3_evm.h            |  1 +
 include/configs/omap3_evm_quick_nand.h |  1 +
 include/configs/omap3_igep00x0.h       |  1 +
 include/configs/omap3_overo.h          |  1 +
 include/configs/siemens-am33x-common.h |  1 +
 include/configs/tam3517-common.h       |  2 +-
 include/configs/tricorder.h            |  2 +-
 17 files changed, 43 insertions(+), 15 deletions(-)

doc/README.nand +0 -0

index 8a4252b..25a4412 100644

doc/README.nand +23 -0

        done by GPMC controller.
 
+   CONFIG_NAND_OMAP_ECCSCHEME
+       On OMAP platforms, this CONFIG specifies NAND ECC scheme.
+       It can take following values:
+       OMAP_ECC_HAM1_CODE_SW
+               1-bit Hamming code using software lib.
+               (for legacy devices only)
+       OMAP_ECC_HAM1_CODE_HW
+               1-bit Hamming code using GPMC hardware.
+               (for legacy devices only)
+       OMAP_ECC_BCH4_CODE_HW_DETECTION_SW
+               4-bit BCH code (unsupported)
+       OMAP_ECC_BCH4_CODE_HW
+               4-bit BCH code (unsupported)
+       OMAP_ECC_BCH8_CODE_HW_DETECTION_SW
+               8-bit BCH code with
+               - ecc calculation using GPMC hardware engine,
+               - error detection using software library.
+               - requires CONFIG_BCH to enable software BCH library
+               (For legacy device which do not have ELM h/w engine)
+       OMAP_ECC_BCH8_CODE_HW
+               8-bit BCH code with
+               - ecc calculation using GPMC hardware engine,
+               - error detection using ELM hardware engine.
 
 NOTE:
 =====

doc/README.omap3 +0 -0

index 1fbe79d..a62c357 100644

on
OMAP3 devices we can use the BCH library in lib/bch.c. To do so add

CONFIG_BCH
-to enable the library and CONFIG_NAND_OMAP_BCH8 to to enable

BCH8_SW.
The NAND OOB layout is the same as in linux kernel, if the linux

BCH8
implementation for OMAP3 works for you so the u-boot version should

When you require the SPL to read with BCH8 there are two more

index 474a568..4f43ba9 100644

include/configs/devkit8000.h +1 -0

@@ -327,6 +327,7 @@
 
 #define CONFIG_SYS_NAND_ECCSIZE                512
 #define CONFIG_SYS_NAND_ECCBYTES       3
+#define CONFIG_NAND_OMAP_ECCSCHEME     OMAP_ECC_HAM1_CODE_HW
 
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 

include/configs/mcx.h +0 -1

index a2f7cf7..dcd29ce 100644
@@ -353,7 +353,6 @@
 #define CONFIG_SPL_FRAMEWORK
 #define CONFIG_SPL_BOARD_INIT
 #define CONFIG_SPL_NAND_SIMPLE
-#define CONFIG_SPL_NAND_SOFTECC
 
 #define CONFIG_SPL_LIBCOMMON_SUPPORT
 #define CONFIG_SPL_LIBDISK_SUPPORT

index 84b4aee..e0f0262 100644

include/configs/omap3_overo.h +1 -0

@@ -324,6 +324,7 @@
                                                10, 11, 12, 13}
 #define CONFIG_SYS_NAND_ECCSIZE                512
 #define CONFIG_SYS_NAND_ECCBYTES       3
+#define CONFIG_NAND_OMAP_ECCSCHEME     OMAP_ECC_HAM1_CODE_HW
 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 #define CONFIG_SYS_NAND_U_BOOT_OFFS    0x80000
 

include/configs/siemens-am33x-common.h +0 -0

index 85d6dc2..f37653f 100644

NAND */

                                                        /* devices

include/configs/tricorder.h +0 -1

 #define CONFIG_SYS_NAND_U_BOOT_START   CONFIG_SYS_TEXT_BASE
 
--

1.8.1

Dear Pekon,

thanks for your mail. This ECC topic is of some complexity. :(

I am close to solve a huge problem here, switching boards from 1bit-SW-ECC to BCH4.
The only missing part is, that OMAP xloader and uboot calculates the BCH4 ECC values than Sitara XLoader
(although the x-loader binaries are identical).
Main problem is not that this is different to Linux - this is not nice, but not a problem. I solved this by implementing a
second linux compatible BCH4 in uboot (which works on both platforms). Problem is, that BCH4 (as it is implemented in aragos xloader) seems not to work on OMAP3503.
And it is not understood by me, why this is not working, or what can the reason for this.

You suggestions address kernel/uboot changes. For this I have already a solution.
I am running into other troubles if I shift to your suggestions, and I can't see an improvement for
the xloader problem.
I know, nowadays the xloader is SPL and is derived from uboot. But I haven't the power to completely change everything again. Frankly speaking, I afraid another nightmare here. Unfortunatly TI doesn't have an newer SDK for OMAP3503/AM3703. Is it true, that in this Arago or TI SDK the only functional ECC scheme are 1 bit SW and 1 bit HW (for xloader)?

For me it seems (if you check my logs) that in xloader the omap_calculate_ecc_bch4() uses hardware GPMC registers. Main question: why this doens't work or give different results in OMAP?

The version I take over for uboot and kernel (according to Technical Note from Micron tn2971_software_bch_ecc_on_linux.pdf), this functions. The counterpart for this seems to me in bch.c encode_bch(), which seems to run completly independent on hardware.

Please understand my situation. At TI forum I asked since monthes with no real help. So I started my work and succeeded 90%.