diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi
index 831810583823b78f735a11b354c715461f376401..41659df0ea6716a5d5de8799d5b2551b8069bd17 100644
--- a/arch/arm/boot/dts/am33xx.dtsi
+++ b/arch/arm/boot/dts/am33xx.dtsi
@@ -356,6 +356,7 @@
 			reg = <0x480C8000 0x200>;
 			interrupts = <77>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <8>;
 			mbox_wkupm3: wkup_m3 {
diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index 46660ffd2b65bbe90100b2b251b29fb6528afe31..4367f75501832b3538baf8b4b7752c6ccf1fbbda 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -168,6 +168,7 @@
 			reg = <0x480C8000 0x200>;
 			interrupts = <GIC_SPI 77 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <8>;
 			mbox_wkupm3: wkup_m3 {
diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
index b8c9c671427eabd4a9205e1a9f9c13a438f1dfef..2af786794d7321f85767a21e9182f60a9d83bdd6 100644
--- a/arch/arm/boot/dts/dra7.dtsi
+++ b/arch/arm/boot/dts/dra7.dtsi
@@ -425,6 +425,7 @@
 				     <GIC_SPI 135 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 134 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox1";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <3>;
 			ti,mbox-num-fifos = <8>;
 			status = "disabled";
@@ -438,6 +439,7 @@
 				     <GIC_SPI 239 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 240 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox2";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -451,6 +453,7 @@
 				     <GIC_SPI 243 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 244 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox3";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -464,6 +467,7 @@
 				     <GIC_SPI 247 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 248 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox4";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -477,6 +481,7 @@
 				     <GIC_SPI 251 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 252 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox5";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -490,6 +495,7 @@
 				     <GIC_SPI 255 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 256 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox6";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -503,6 +509,7 @@
 				     <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 260 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox7";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -516,6 +523,7 @@
 				     <GIC_SPI 263 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 264 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox8";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -529,6 +537,7 @@
 				     <GIC_SPI 267 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox9";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -542,6 +551,7 @@
 				     <GIC_SPI 271 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 272 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox10";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -555,6 +565,7 @@
 				     <GIC_SPI 275 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 276 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox11";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -568,6 +579,7 @@
 				     <GIC_SPI 279 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 280 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox12";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
@@ -581,6 +593,7 @@
 				     <GIC_SPI 381 IRQ_TYPE_LEVEL_HIGH>,
 				     <GIC_SPI 382 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox13";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <12>;
 			status = "disabled";
diff --git a/arch/arm/boot/dts/omap2420.dtsi b/arch/arm/boot/dts/omap2420.dtsi
index ae89aad01595890511f241c5dd932505e24fa78e..e2b2e93d7b6160f364bcb4832cc593c09f9627ac 100644
--- a/arch/arm/boot/dts/omap2420.dtsi
+++ b/arch/arm/boot/dts/omap2420.dtsi
@@ -157,6 +157,7 @@
 			interrupts = <26>, <34>;
 			interrupt-names = "dsp", "iva";
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <6>;
 			mbox_dsp: dsp {
diff --git a/arch/arm/boot/dts/omap2430.dtsi b/arch/arm/boot/dts/omap2430.dtsi
index b56d71611026571d5486badcadce45749b97a1a9..0dc8de2782b1871772150b3a62ab7a92685da56a 100644
--- a/arch/arm/boot/dts/omap2430.dtsi
+++ b/arch/arm/boot/dts/omap2430.dtsi
@@ -247,6 +247,7 @@
 			reg = <0x48094000 0x200>;
 			interrupts = <26>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <4>;
 			ti,mbox-num-fifos = <6>;
 			mbox_dsp: dsp {
diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
index d0e884d3a7372f003f1777aeba1f6ccc15c2e26c..8db7def81c286efe43ca552f0580345f86188750 100644
--- a/arch/arm/boot/dts/omap3.dtsi
+++ b/arch/arm/boot/dts/omap3.dtsi
@@ -332,6 +332,7 @@
 			ti,hwmods = "mailbox";
 			reg = <0x48094000 0x200>;
 			interrupts = <26>;
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <2>;
 			ti,mbox-num-fifos = <2>;
 			mbox_dsp: dsp {
diff --git a/arch/arm/boot/dts/omap4.dtsi b/arch/arm/boot/dts/omap4.dtsi
index 878c979203d09ea403577317e3211e85329303fe..a46eab82d2da2943f1ddd500e58707190e33a111 100644
--- a/arch/arm/boot/dts/omap4.dtsi
+++ b/arch/arm/boot/dts/omap4.dtsi
@@ -661,6 +661,7 @@
 			reg = <0x4a0f4000 0x200>;
 			interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <3>;
 			ti,mbox-num-fifos = <8>;
 			mbox_ipu: mbox_ipu {
diff --git a/arch/arm/boot/dts/omap5.dtsi b/arch/arm/boot/dts/omap5.dtsi
index 256b7f69e45b4cba84b2bfa85543545374ce6f02..b321fdf42c9f3c51e3a59d4b51b27a08f4fcaba4 100644
--- a/arch/arm/boot/dts/omap5.dtsi
+++ b/arch/arm/boot/dts/omap5.dtsi
@@ -651,6 +651,7 @@
 			reg = <0x4a0f4000 0x200>;
 			interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "mailbox";
+			#mbox-cells = <1>;
 			ti,mbox-num-users = <3>;
 			ti,mbox-num-fifos = <8>;
 			mbox_ipu: mbox_ipu {