diff --git a/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt b/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
index 23d83fa7609f..b219626a5403 100644
--- a/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
+++ b/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
@@ -82,6 +82,7 @@ Optional properties:
   - dai-format		: audio format, for details see simple-card.yaml.
   - frame-inversion	: dai-link uses frame clock inversion, for details see simple-card.yaml.
   - bitclock-inversion	: dai-link uses bit clock inversion, for details see simple-card.yaml.
+  - mclk-id		: main clock id, specific for each card configuration.
 
 Optional unless SSI is selected as a CPU DAI: