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authorpekon gupta <pekon@ti.com>2013-11-18 19:03:01 +0530
committerScott Wood <scottwood@freescale.com>2013-11-21 13:33:41 -0600
commit3f719069c884284b2457448a7afe32b02bd4f782 (patch)
treeebcbf9a507b4079b6c1842503f3fd1233bfb066d /doc
parentd016dc42cedbf6102e100fa9ecb58462edfb14f8 (diff)
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mtd: nand: omap: add CONFIG_NAND_OMAP_ECCSCHEME for selection of ecc-scheme
This patch adds new CONFIG_NAND_OMAP_ECCSCHEME, replacing other distributed 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 to select other ecc-schemes also supported in hardware. like; - most of OMAP3 SoC platforms use only 1-bit Hamming ecc-scheme, inspite the fact that they can use higher ecc-schemes like 8-bit ecc-schemes with software based error detection (OMAP_ECC_BCH4_CODE_HW_DETECTION_SW). - most of AM33xx SoC plaforms use 8-bit BCH ecc-scheme for now, but hardware supports BCH16 ecc-scheme also. 2) Different platforms use different CONFIG_xx to select ecc-schemes, which adds confusion for user while migrating platforms. - *CONFIG_NAND_OMAP_ELM* which enables ELM hardware engine, selects only 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; BCH4, and BCH16 (in future). - *CONFIG_NAND_OMAP_BCH8* selects 8-bit BCH ecc-scheme with s/w based error correction (OMAP_ECC_BCH8_CODE_HW_DETECTION_SW). - *CONFIG_SPL_NAND_SOFTECC* selects 1-bit Hamming ecc-scheme using s/w library Thus adding new *CONFIG_NAND_OMAP_ECCSCHEME* de-couples ecc-scheme dependency on SoC platform and NAND driver. And user can select ecc-scheme independently foreach board. However, selection some hardware based ecc-schemes (OMAP_ECC_BCHx_CODE_HW) still depends on presence of ELM hardware engine on SoC. (Refer doc/README.nand) Signed-off-by: Pekon Gupta <pekon@ti.com>
Diffstat (limited to 'doc')
-rw-r--r--doc/README.nand23
-rw-r--r--doc/README.omap33
2 files changed, 24 insertions, 2 deletions
diff --git a/doc/README.nand b/doc/README.nand
index 487548f..b91f198 100644
--- a/doc/README.nand
+++ b/doc/README.nand
@@ -208,6 +208,29 @@ Platform specific options
detection. However ECC calculation on such plaforms would still be
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:
=====
diff --git a/doc/README.omap3 b/doc/README.omap3
index 1fbe79d..a62c357 100644
--- a/doc/README.omap3
+++ b/doc/README.omap3
@@ -161,8 +161,7 @@ BCH8
To enable hardware assisted BCH8 (8-bit BCH [Bose, Chaudhuri, Hocquenghem]) 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 hardware assisted
-syndrom generation to your board config.
+and set CONFIG_NAND_OMAP_ECCSCHEME=5 (refer README.nand) for selecting BCH8_SW.
The NAND OOB layout is the same as in linux kernel, if the linux kernel BCH8
implementation for OMAP3 works for you so the u-boot version should also.
When you require the SPL to read with BCH8 there are two more configs to