[media] dt-bindings: media/s5p-cec.txt: document needs-hpd property

Needed for boards that wire the CEC pin in such a way that it
is unavailable when the HPD is low.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/Documentation/devicetree/bindings/media/s5p-cec.txt b/Documentation/devicetree/bindings/media/s5p-cec.txt
index 4bb08d9d940be0473d937ad7c7c97d87c5d517d9..261af4d1a791678cf5bfa04624ba9d4dc86576b9 100644 (file)
--- a/Documentation/devicetree/bindings/media/s5p-cec.txt
+++ b/Documentation/devicetree/bindings/media/s5p-cec.txt
@@ -17,6 +17,12 @@ Required properties:
   - samsung,syscon-phandle - phandle to the PMU system controller
   - hdmi-phandle - phandle to the HDMI controller
 
+Optional:
+  - needs-hpd : if present the CEC support is only available when the HPD
+    is high. Some boards only let the CEC pin through if the HPD is high, for
+    example if there is a level converter that uses the HPD to power up
+    or down.
+
 Example:
 
 hdmicec: cec@100B0000 {