diff --git a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
index 1b662d7171a0..503c6dbac1b2 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
@@ -9,6 +9,11 @@ Required properties:
 - clocks:		Phandlers to the clocks.
 - clock-names:		Must be "hclock", "multclk", "baseclk";
 
+Optional properties:
+- microchip,sdcal-inverted: when present, polarity on the SDCAL SoC pin is
+  inverted. The default polarity for this signal is described in the datasheet.
+  For instance on SAMA5D2, the pin is usually tied to the GND with a resistor
+  and a capacitor (see "SDMMC I/O Calibration" chapter).
 
 Example: