diff --git a/arch/arm64/boot/dts/ti/k3-am642-evm.dts b/arch/arm64/boot/dts/ti/k3-am642-evm.dts
index dc69db2d10c3..2e75cd68f8b7 100644
--- a/arch/arm64/boot/dts/ti/k3-am642-evm.dts
+++ b/arch/arm64/boot/dts/ti/k3-am642-evm.dts
@@ -469,6 +469,22 @@
 	status = "disabled";
 };
 
+&main_r5fss0_core0 {
+	mboxes = <&mailbox0_cluster2 &mbox_main_r5fss0_core0>;
+};
+
+&main_r5fss0_core1 {
+	mboxes = <&mailbox0_cluster2 &mbox_main_r5fss0_core1>;
+};
+
+&main_r5fss1_core0 {
+	mboxes = <&mailbox0_cluster4 &mbox_main_r5fss1_core0>;
+};
+
+&main_r5fss1_core1 {
+	mboxes = <&mailbox0_cluster4 &mbox_main_r5fss1_core1>;
+};
+
 &serdes_ln_ctrl {
 	idle-states = <AM64_SERDES0_LANE0_PCIE0>;
 };
diff --git a/arch/arm64/boot/dts/ti/k3-am642-sk.dts b/arch/arm64/boot/dts/ti/k3-am642-sk.dts
index 40124007259d..4abddea92cf5 100644
--- a/arch/arm64/boot/dts/ti/k3-am642-sk.dts
+++ b/arch/arm64/boot/dts/ti/k3-am642-sk.dts
@@ -368,6 +368,22 @@
 	status = "disabled";
 };
 
+&main_r5fss0_core0 {
+	mboxes = <&mailbox0_cluster2 &mbox_main_r5fss0_core0>;
+};
+
+&main_r5fss0_core1 {
+	mboxes = <&mailbox0_cluster2 &mbox_main_r5fss0_core1>;
+};
+
+&main_r5fss1_core0 {
+	mboxes = <&mailbox0_cluster4 &mbox_main_r5fss1_core0>;
+};
+
+&main_r5fss1_core1 {
+	mboxes = <&mailbox0_cluster4 &mbox_main_r5fss1_core1>;
+};
+
 &pcie0_rc {
 	status = "disabled";
 };