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

[karo-tx-uboot.git] / doc / README.nand

diff --git a/doc/README.nand b/doc/README.nand
index 913e9b50b804535acf9adc5176cdaae4132e51a1..b91f1985d183d0c3681567293cae7d666139a441 100644 (file)
--- a/doc/README.nand
+++ b/doc/README.nand
@@ -104,6 +104,16 @@ Configuration Options:
    CONFIG_SYS_MAX_NAND_DEVICE
       The maximum number of NAND devices you want to support.
 
+   CONFIG_SYS_NAND_MAX_ECCPOS
+      If specified, overrides the maximum number of ECC bytes
+      supported.  Useful for reducing image size, especially with SPL.
+      This must be at least 48 if nand_base.c is used.
+
+   CONFIG_SYS_NAND_MAX_OOBFREE
+      If specified, overrides the maximum number of free OOB regions
+      supported.  Useful for reducing image size, especially with SPL.
+      This must be at least 2 if nand_base.c is used.
+
    CONFIG_SYS_NAND_MAX_CHIPS
       The maximum number of NAND chips per device to be supported.
 
@@ -169,6 +179,59 @@ Configuration Options:
       Please convert your driver even if you don't need the extra
       flexibility, so that one day we can eliminate the old mechanism.
 
+
+   CONFIG_SYS_NAND_ONFI_DETECTION
+       Enables detection of ONFI compliant devices during probe.
+       And fetching device parameters flashed on device, by parsing
+       ONFI parameter page.
+
+   CONFIG_BCH
+       Enables software based BCH ECC algorithm present in lib/bch.c
+       This is used by SoC platforms which do not have built-in ELM
+       hardware engine required for BCH ECC correction.
+
+
+Platform specific options
+=========================
+   CONFIG_NAND_OMAP_GPMC
+       Enables omap_gpmc.c driver for OMAPx and AMxxxx platforms.
+       GPMC controller is used for parallel NAND flash devices, and can
+       do ECC calculation (not ECC error detection) for HAM1, BCH4, BCH8
+       and BCH16 ECC algorithms.
+
+   CONFIG_NAND_OMAP_ELM
+       Enables omap_elm.c driver for OMAPx and AMxxxx platforms.
+       ELM controller is used for ECC error detection (not ECC calculation)
+       of BCH4, BCH8 and BCH16 ECC algorithms.
+       Some legacy platforms like OMAP3xx do not have in-built ELM h/w engine,
+       thus such SoC platforms need to depend on software library for ECC error
+       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:
 =====