doc: KARO: update FDT handling description

diff --git a/doc/README.KARO-FDT b/doc/README.KARO-FDT
index 4bf01fac29608451306ad3ebaa8981c2c3df474c..092276fbc3163ea4782b41cea17afcb208faa748 100644 (file)
--- a/doc/README.KARO-FDT
+++ b/doc/README.KARO-FDT
@@ -4,10 +4,11 @@
 The 'fdt' command can be used to manipulate the device tree (DT) data
 that is passed from U-Boot to Linux.
 
-- 'fdt boardsetup' will trim out some device nodes according to
-  environment settings:
+- 'fdt boardsetup' (which is automatically being run by the 'bootm'
+  command) will disable some device nodes according to environment
+  settings:
 
-Environment setting            removed nodes
+Environment setting            disabled nodes
 ---------------------------------------------
 otg_mode=host                  usbh1
 otg_mode=device                        usbotg
@@ -20,16 +21,32 @@ touchpanel=<UNSET>          <both of the above>
 Note: This command is automatically executed when booting Linux via
       'run bootm_cmd'.
 
-- 'fdt rm' and 'fdt add' can be used to remove/create additional nodes.
+- 'fdt rm' and 'fdt mknode' can be used to remove/create additional nodes.
+
+- 'fdt set' can be used to change properties or add new properties to
+  existing nodes.
 
 The whole DT data can be saved to and reloaded from the flash partition
 'dtb' (or any other partition):
   nand erase.part dtb
   nand write.jffs2 ${fdtaddr} dtb ${fdtsize}
+The predefined variable 'fdtsave' contains these commands as a macro
+to facilitate the update of the 'dtb' partition with the currently
+active FDT. Thus:
+  'run fdtsave' will achive the same as above commands.
 
-If a DT is loaded from flash which should not be further manipulated
-upon booting Linux, the string 'fdt boardsetup;' should be removed
-from the 'bootm_cmd' environment variable.
-
-Loading the DT data:
+(Re)Loading the DT data from flash:
   nand read ${fdtaddr} dtb
+
+Enabling/Disabling individual nodes in FDT:
+Most device nodes in FDT use a property named 'status' that can be set
+to either 'disabled' or 'okay' to disable or enable the device.
+This property can be manipulated
+  fdt set /<path> status disabled
+  fdt set /<path> status okay
+
+e.g.: fdt set /soc/aips-bus@02100000/ethernet@02188000 status disabled
+      will disable the ethernet interface on a TX6.
+
+Refer to Linux/TX*-driver.pdf for a complete list of the device paths
+for the individual TX modules.