[PATCH v3 1/4] dt-bindings: media: snps,dw-hdmi-rx: add #sound-dai-cells

[Igor Paunovic <royalnet026@gmail.com>]

The HDMI RX controller can expose the audio embedded in the incoming
HDMI stream as an ALSA capture device. Document the #sound-dai-cells
property so that a sound card can reference the HDMI RX audio DAI.

Signed-off-by: Igor Paunovic <royalnet026@gmail.com>
---
Changes in v3:
- no changes

Changes in v2 (all suggested by Sebastian Reichel):
- reworded the commit message to describe the hardware
- property description now documents the DAI indexes (0 = I2S,
  1 = S/PDIF)
- moved the consumer reference into the binding example

 .../devicetree/bindings/media/snps,dw-hdmi-rx.yaml       | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/media/snps,dw-hdmi-rx.yaml b/Documentation/devicetree/bindings/media/snps,dw-hdmi-rx.yaml
index b7f6c87..fa6cd0d 100644
--- a/Documentation/devicetree/bindings/media/snps,dw-hdmi-rx.yaml
+++ b/Documentation/devicetree/bindings/media/snps,dw-hdmi-rx.yaml
@@ -78,6 +78,13 @@ properties:
       The phandle of the syscon node for the Video Output GRF register
       to enable EDID transfer through SDAIN and SCLIN.
 
+  "#sound-dai-cells":
+    const: 1
+    description:
+      The HDMI RX controller has two digital audio interfaces, one for
+      I2S and one for S/PDIF. The DAI cell selects the interface, 0 for
+      I2S and 1 for S/PDIF.
+
 required:
   - compatible
   - reg
@@ -129,4 +136,6 @@ examples:
       pinctrl-0 = <&hdmim1_rx_cec &hdmim1_rx_hpdin &hdmim1_rx_scl &hdmim1_rx_sda &hdmirx_5v_detection>;
       pinctrl-names = "default";
       hpd-gpios = <&gpio1 22 GPIO_ACTIVE_LOW>;
+      /* referenced by a sound card as <&hdmi_receiver 0> (0: I2S, 1: S/PDIF) */
+      #sound-dai-cells = <1>;
     };
-- 
2.53.0