diff --git a/Documentation/devicetree/bindings/mmc/mmci.txt b/Documentation/devicetree/bindings/mmc/mmci.txt
index 6d3c626e017d2ede605dc02011defaa5130a50dc..4ec921e4bf344f7b2594baff99cb8447cc63c0d4 100644
--- a/Documentation/devicetree/bindings/mmc/mmci.txt
+++ b/Documentation/devicetree/bindings/mmc/mmci.txt
@@ -28,6 +28,8 @@ specific for ux500 variant:
 - st,sig-pin-fbclk       : feedback clock signal pin used.
 
 specific for sdmmc variant:
+- reg			 : a second base register may be defined if a delay
+                           block is present and used for tuning.
 - st,sig-dir             : signal direction polarity used for cmd, dat0 dat123.
 - st,neg-edge            : data & command phase relation, generated on
                            sd clock falling edge.