diff --git a/include/linux/phy/phy-mipi-dphy.h b/include/linux/phy/phy-mipi-dphy.h
index a877ffee845deb4f25dfa45a492c513caa383b65..0f57ef46a8b55e617ecf669f0aff651314180581 100644
--- a/include/linux/phy/phy-mipi-dphy.h
+++ b/include/linux/phy/phy-mipi-dphy.h
@@ -6,6 +6,19 @@
 #ifndef __PHY_MIPI_DPHY_H_
 #define __PHY_MIPI_DPHY_H_
 
+/**
+ * enum phy_mipi_dphy_submode - MIPI D-PHY sub-mode
+ *
+ * A MIPI D-PHY can be used to transmit or receive data.
+ * Since some controllers can support both, the direction to enable is specified
+ * with the PHY sub-mode. Transmit is assumed by default with phy_set_mode.
+ */
+
+enum phy_mipi_dphy_submode {
+	PHY_MIPI_DPHY_SUBMODE_TX = 0,
+	PHY_MIPI_DPHY_SUBMODE_RX,
+};
+
 /**
  * struct phy_configure_opts_mipi_dphy - MIPI D-PHY configuration set
  *