[PATCH 2/2] dt-bindings: sound: sun6i-spdif: Document that the RX channel can be missing

[Maxime Ripard <maxime.ripard@xxxxxxxxxxx>]

Not all controllers using the A31 SPDIF binding actually have some RX
capabilities, and therefore on some controllers we don't have the option to
set an RX DMA channel.

This was already done in the DTSI, but the binding itself was never
updated.

Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
---
 Documentation/devicetree/bindings/sound/allwinner,sun6i-a31-spdif.yaml | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/allwinner,sun6i-a31-spdif.yaml b/Documentation/devicetree/bindings/sound/allwinner,sun6i-a31-spdif.yaml
index 7329d9fcf34c..800f794fafe0 100644
--- a/Documentation/devicetree/bindings/sound/allwinner,sun6i-a31-spdif.yaml
+++ b/Documentation/devicetree/bindings/sound/allwinner,sun6i-a31-spdif.yaml
@@ -44,14 +44,24 @@ properties:
       - const: spdif
 
   dmas:
+    minItems: 1
+    maxItems: 2
     items:
       - description: RX DMA Channel
       - description: TX DMA Channel
+    description:
+      Some controllers cannot receive but can only transmit data. In
+      such a case, the RX DMA channel is to be omitted.
 
   dma-names:
-    items:
-      - const: rx
-      - const: tx
+    minItems: 1
+    maxItems: 2
+    enum:
+      - rx
+      - tx
+    description:
+      Some controllers cannot receive but can only transmit data. In
+      such a case, the RX name is to be omitted.
 
   resets:
     maxItems: 1
-- 
git-series 0.9.1