fs: separate CONFIG_FS_{FAT, EXT4} from CONFIG_CMD_{FAT, EXT*}

This makes the FAT and ext4 filesystem implementations build if
CONFIG_FS_{FAT,EXT4} are defined, rather than basing the build on
whether CONFIG_CMD_{FAT,EXT*} are defined. This will allow the
filesystems to be built separately from the filesystem-specific commands
that use them. This paves the way for the creation of filesystem-generic
commands that used the filesystems, without requiring the filesystem-
specific commands.

Minor documentation changes are made for this change.

The new config options are automatically selected by the old config
options to retain backwards-compatibility.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/README.ext4 b/doc/README.ext4
index b3ea8b7..b7d0ad3 100644
--- a/doc/README.ext4
+++ b/doc/README.ext4
@@ -1,15 +1,28 @@
 This patch series adds support for ext4 ls,load and write features in uboot
 Journaling is supported for write feature.
 
+To enable support for the ext4 (and ext2) filesystem implementation,
+#define CONFIG_FS_EXT4
+
+If you want write support,
+#define CONFIG_EXT4_WRITE
+
 To Enable ext2 ls and load commands, modify the board specific config file with
 #define CONFIG_CMD_EXT2
+This automatically defines CONFIG_FS_EXT4 for you.
 
 To Enable ext4 ls and load commands, modify the board specific config file with
 #define CONFIG_CMD_EXT4
+This automatically defines CONFIG_FS_EXT4 for you.
 
 To enable ext4 write command, modify the board specific config file with
 #define CONFIG_CMD_EXT4
 #define CONFIG_CMD_EXT4_WRITE
+These automatically define CONFIG_FS_EXT4 and CONFIG_EXT4_WRITE for you.
+
+Also relevant are the generic filesystem commands,
+#define CONFIG_CMD_FS_GENERIC
+This does not automatically enable EXT4 support for you.
 
 Steps to test: