Merge the new NAND code (testing-NAND brach); see doc/README.nand

[kernel/u-boot.git] / doc / README.nand

diff --git a/doc/README.nand b/doc/README.nand
index 0f2bdc5..cd7608c 100644 (file)
--- a/doc/README.nand
+++ b/doc/README.nand
@@ -1,5 +1,9 @@
 NAND FLASH commands and notes
 
+
+See NOTE below!!!
+
+
 # (C) Copyright 2003
 # Dave Ellis, SIXNET, dge@sixnetio.com
 #
@@ -173,3 +177,34 @@ More Definitions:
    #define NAND_ChipID_UNKNOWN 0x00
    #define NAND_MAX_FLOORS 1
    #define NAND_MAX_CHIPS 1
+
+
+
+NOTE:
+=====
+
+We now use a complete rewrite of the NAND code based on what is in
+2.6.12 Linux kernel.
+
+The old NAND handling code has been re-factored and is now confined
+to only board-specific files and - unfortunately - to the DoC code
+(see below). A new configuration variable has been introduced:
+CFG_NAND_LEGACY, which has to be defined in the board config file if
+that board uses legacy code. If CFG_NAND_LEGACY is defined, the board
+specific config.mk file should also have "BOARDLIBS =
+drivers/nand_legacy/libnand_legacy.a". For boards using the new NAND
+approach (PPChameleon and netstar at the moment) no variable is
+necessary, but the config.mk should have "BOARDLIBS =
+drivers/nand/libnand.a".
+
+The necessary changes have been made to all affected boards, and no
+build breakage has been introduced, except for NETTA and NETTA_ISDN
+targets from MAKEALL. This is due to the fact that these two boards
+use JFFS, which has been adopted to use the new NAND, and at the same
+time use NAND in legacy mode. The breakage will disappear when the
+board-specific code is changed to the new NAND.
+
+As mentioned above, the legacy code is still used by the DoC subsystem. 
+The consequence of this is that the legacy NAND can't be removed  from 
+the tree until the DoC is ported to use the new NAND support (or boards 
+with DoC will break).