Add a description of the target index overlay method to the overlay
documention file.

Signed-off-by: Pantelis Antoniou <pantelis.anton...@konsulko.com>
---
 Documentation/devicetree/overlay-notes.txt | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/overlay-notes.txt 
b/Documentation/devicetree/overlay-notes.txt
index d418a6c..6995fc1 100644
--- a/Documentation/devicetree/overlay-notes.txt
+++ b/Documentation/devicetree/overlay-notes.txt
@@ -100,6 +100,10 @@ Finally, if you need to remove all overlays in one-go, 
just call
 of_overlay_destroy_all() which will remove every single one in the correct
 order.
 
+If your board has multiple slots/places where a single overlay can work
+and each slot is defined by a node, you can use the
+of_overlay_create_target_index() method to select the target.
+
 Overlay DTS Format
 ------------------
 
@@ -110,9 +114,11 @@ The DTS of an overlay should have the following format:
 
        fragment@0 {    /* first child node */
 
-               target=<phandle>;       /* phandle target of the overlay */
+               /* phandle target of the overlay */
+               target=<phandle> [, <phandle>, ...];
        or
-               target-path="/path";    /* target path of the overlay */
+               /* target path of the overlay */
+               target-path="/path" [ , "/path", ...];
 
                __overlay__ {
                        property-a;     /* add property-a to the target */
@@ -131,3 +137,7 @@ Using the non-phandle based target method allows one to use 
a base DT which does
 not contain a __symbols__ node, i.e. it was not compiled with the -@ option.
 The __symbols__ node is only required for the target=<phandle> method, since it
 contains the information required to map from a phandle to a tree location.
+
+Using a target index requires the use of a selector target on the call to
+of_overlay_create_target_index(). I.e. passing an index of 0 will select the
+target in the foo node, an index of 1 the bar node, etc.
-- 
1.7.12

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