diff --git a/headers/private/graphics/common/dp.h b/headers/private/graphics/common/dp.h
index b6f01ede41..7837c7f295 100644
--- a/headers/private/graphics/common/dp.h
+++ b/headers/private/graphics/common/dp.h
@@ -34,7 +34,7 @@ typedef struct {
 } dp_info;
 
 typedef struct {
-	uint16	address;
+	uint32	address;
 	uint8	request;
 	uint8	reply;
 	void*	buffer;
diff --git a/src/add-ons/accelerants/radeon_hd/displayport.cpp b/src/add-ons/accelerants/radeon_hd/displayport.cpp
index 9249b6e468..6b7f9f09c2 100644
--- a/src/add-ons/accelerants/radeon_hd/displayport.cpp
+++ b/src/add-ons/accelerants/radeon_hd/displayport.cpp
@@ -129,8 +129,8 @@ dp_aux_transaction(uint32 connectorIndex, dp_aux_msg* message)
 
 	uint8 auxMessage[20];
 	auxMessage[0] = message->address & 0xff;
-	auxMessage[1] = message->address >> 8;
-	auxMessage[2] = message->request << 4;
+	auxMessage[1] = (message->address >> 8) & 0xff;
+	auxMessage[2] = (message->request << 4) | ((message->address >> 16) & 0xf);
 	auxMessage[3] = message->size ? (message->size - 1) : 0;
 
 	if (message->size == 0)
@@ -188,9 +188,9 @@ dp_aux_transaction(uint32 connectorIndex, dp_aux_msg* message)
 
 
 void
-dpcd_reg_write(uint32 connectorIndex, uint16 address, uint8 value)
+dpcd_reg_write(uint32 connectorIndex, uint32 address, uint8 value)
 {
-	//TRACE("%s: connector(%" B_PRId32 "): 0x%" B_PRIx16 " -> 0x%" B_PRIx8 "\n",
+	//TRACE("%s: connector(%" B_PRId32 "): 0x%" B_PRIx32 " -> 0x%" B_PRIx8 "\n",
 	//	__func__, connectorIndex, address, value);
 	dp_aux_msg message;
 	memset(&message, 0, sizeof(message));
@@ -209,9 +209,9 @@ dpcd_reg_write(uint32 connectorIndex, uint16 address, uint8 value)
 
 
 uint8
-dpcd_reg_read(uint32 connectorIndex, uint16 address)
+dpcd_reg_read(uint32 connectorIndex, uint32 address)
 {
-	//TRACE("%s: connector(%" B_PRId32 "): read 0x%" B_PRIx16 ".\n",
+	//TRACE("%s: connector(%" B_PRId32 "): read 0x%" B_PRIx32 ".\n",
 	//	__func__, connectorIndex, address);
 	uint8 response[3];
 
@@ -234,7 +234,7 @@ dpcd_reg_read(uint32 connectorIndex, uint16 address)
 
 
 status_t
-dp_aux_get_i2c_byte(uint32 connectorIndex, uint16 address, uint8* data,
+dp_aux_get_i2c_byte(uint32 connectorIndex, uint32 address, uint8* data,
 	bool start, bool stop)
 {
 	uint8 reply[3];
@@ -284,7 +284,7 @@ dp_aux_get_i2c_byte(uint32 connectorIndex, uint16 address, uint8* data,
 
 
 status_t
-dp_aux_set_i2c_byte(uint32 connectorIndex, uint16 address, uint8* data,
+dp_aux_set_i2c_byte(uint32 connectorIndex, uint32 address, uint8* data,
 	bool start, bool stop)
 {
 	dp_aux_msg message;
diff --git a/src/add-ons/accelerants/radeon_hd/displayport.h b/src/add-ons/accelerants/radeon_hd/displayport.h
index 9432401ef4..87622ffb0e 100644
--- a/src/add-ons/accelerants/radeon_hd/displayport.h
+++ b/src/add-ons/accelerants/radeon_hd/displayport.h
@@ -23,15 +23,15 @@
 #define DP_TPS3_SUPPORTED (1 << 6) // Stored within MAX_LANE_COUNT
 
 
-uint8 dpcd_reg_read(uint32 connectorIndex, uint16 address);
-void dpcd_reg_write(uint32 connectorIndex, uint16 address, uint8 value);
+uint8 dpcd_reg_read(uint32 connectorIndex, uint32 address);
+void dpcd_reg_write(uint32 connectorIndex, uint32 address, uint8 value);
 
 // Communication over DisplayPort AUX channel
 status_t dp_aux_transaction(uint32 connectorIndex, dp_aux_msg* message);
 
-status_t dp_aux_set_i2c_byte(uint32 connectorIndex, uint16 address,
+status_t dp_aux_set_i2c_byte(uint32 connectorIndex, uint32 address,
 	uint8* data, bool start, bool stop);
-status_t dp_aux_get_i2c_byte(uint32 connectorIndex, uint16 address,
+status_t dp_aux_get_i2c_byte(uint32 connectorIndex, uint32 address,
 	uint8* data, bool start, bool stop);
 
 uint32 dp_get_link_rate(uint32 connectorIndex, display_mode* mode);