diff --git a/src/northbridge/intel/gm45/gma.c b/src/northbridge/intel/gm45/gma.c
index 24046712b4..00b3fa0a2b 100644
--- a/src/northbridge/intel/gm45/gma.c
+++ b/src/northbridge/intel/gm45/gma.c
@@ -588,8 +588,8 @@ static void gma_ngi(struct device *const dev, struct edid *edid_lvds)
 
 	mmio = res2mmio(gtt_res, 0, 0);
 	printk(BIOS_DEBUG, "VGA EDID\n");
-	intel_gmbus_read_edid(mmio + GMBUS0, 2, 0x50, edid_data_vga,
-			sizeof(edid_data_vga));
+	intel_gmbus_read_edid(mmio + GMBUS0, GMBUS_PORT_VGADDC, 0x50,
+			edid_data_vga, sizeof(edid_data_vga));
 	intel_gmbus_stop(mmio + GMBUS0);
 	vga_edid_status = decode_edid(edid_data_vga,
 				sizeof(edid_data_vga), &edid_vga);
@@ -748,8 +748,8 @@ static void gma_func0_init(struct device *dev)
 	}
 
 	printk(BIOS_DEBUG, "LVDS EDID\n");
-	intel_gmbus_read_edid(mmio + GMBUS0, 3, 0x50, edid_data_lvds,
-			sizeof(edid_data_lvds));
+	intel_gmbus_read_edid(mmio + GMBUS0, GMBUS_PORT_PANEL, 0x50,
+			edid_data_lvds, sizeof(edid_data_lvds));
 	intel_gmbus_stop(mmio + GMBUS0);
 	decode_edid(edid_data_lvds, sizeof(edid_data_lvds), &edid_lvds);
 
diff --git a/src/northbridge/intel/i945/gma.c b/src/northbridge/intel/i945/gma.c
index cba28601d6..37f73ed0eb 100644
--- a/src/northbridge/intel/i945/gma.c
+++ b/src/northbridge/intel/i945/gma.c
@@ -104,8 +104,8 @@ static int intel_gma_init_lvds(struct northbridge_intel_i945_config *conf,
 	       "i915lightup: graphics %p mmio %p addrport %04x physbase %08x\n",
 	       (void *)pgfx, mmiobase, piobase, pphysbase);
 
-	intel_gmbus_read_edid(mmiobase + GMBUS0, 3, 0x50, edid_data,
-			sizeof(edid_data));
+	intel_gmbus_read_edid(mmiobase + GMBUS0, GMBUS_PORT_PANEL, 0x50,
+			edid_data, sizeof(edid_data));
 	decode_edid(edid_data, sizeof(edid_data), &edid);
 	mode = &edid.mode;
 
@@ -663,7 +663,8 @@ static void gma_func0_init(struct device *dev)
 
 		/* probe if VGA is connected and always run */
 		/* VGA init if no LVDS is connected */
-		if (!probe_edid(mmiobase, 3) || probe_edid(mmiobase, 2))
+		if (!probe_edid(mmiobase, GMBUS_PORT_PANEL) ||
+				probe_edid(mmiobase, GMBUS_PORT_VGADDC))
 			err = intel_gma_init_vga(conf,
 				pci_read_config32(dev, 0x5c) & ~0xf,
 				iobase, mmiobase, graphics_base);
diff --git a/src/northbridge/intel/nehalem/gma.c b/src/northbridge/intel/nehalem/gma.c
index 0607f34fb1..56d85230c9 100644
--- a/src/northbridge/intel/nehalem/gma.c
+++ b/src/northbridge/intel/nehalem/gma.c
@@ -712,8 +712,8 @@ static void intel_gma_init(const struct northbridge_intel_nehalem_config *info,
 
 	power_port(mmio);
 
-	intel_gmbus_read_edid(mmio + PCH_GMBUS0, 3, 0x50, edid_data,
-			sizeof(edid_data));
+	intel_gmbus_read_edid(mmio + PCH_GMBUS0, GMBUS_PORT_PANEL, 0x50,
+			edid_data, sizeof(edid_data));
 	intel_gmbus_stop(mmio + PCH_GMBUS0);
 	decode_edid(edid_data,
 		    sizeof(edid_data), &edid);
diff --git a/src/northbridge/intel/sandybridge/gma_ivybridge_lvds.c b/src/northbridge/intel/sandybridge/gma_ivybridge_lvds.c
index cad5078dc3..23ecd44835 100644
--- a/src/northbridge/intel/sandybridge/gma_ivybridge_lvds.c
+++ b/src/northbridge/intel/sandybridge/gma_ivybridge_lvds.c
@@ -182,8 +182,8 @@ int i915lightup_ivy(const struct i915_gpu_controller_info *info,
 
 	enable_port(mmio);
 
-	intel_gmbus_read_edid(mmio + PCH_GMBUS0, 3, 0x50, edid_data,
-			sizeof(edid_data));
+	intel_gmbus_read_edid(mmio + PCH_GMBUS0, GMBUS_PORT_PANEL, 0x50,
+			edid_data, sizeof(edid_data));
 	intel_gmbus_stop(mmio + PCH_GMBUS0);
 	decode_edid(edid_data,
 		    sizeof(edid_data), &edid);
diff --git a/src/northbridge/intel/sandybridge/gma_sandybridge_lvds.c b/src/northbridge/intel/sandybridge/gma_sandybridge_lvds.c
index c3139a99dd..5e8c18855f 100644
--- a/src/northbridge/intel/sandybridge/gma_sandybridge_lvds.c
+++ b/src/northbridge/intel/sandybridge/gma_sandybridge_lvds.c
@@ -176,8 +176,8 @@ int i915lightup_sandy(const struct i915_gpu_controller_info *info,
 
 	power_port(mmio);
 
-	intel_gmbus_read_edid(mmio + PCH_GMBUS0, 3, 0x50, edid_data,
-			sizeof(edid_data));
+	intel_gmbus_read_edid(mmio + PCH_GMBUS0, GMBUS_PORT_PANEL, 0x50,
+			edid_data, sizeof(edid_data));
 	decode_edid(edid_data, sizeof(edid_data), &edid);
 	mode = &edid.mode;
 
diff --git a/src/northbridge/intel/x4x/gma.c b/src/northbridge/intel/x4x/gma.c
index 561e776f24..e91d778774 100644
--- a/src/northbridge/intel/x4x/gma.c
+++ b/src/northbridge/intel/x4x/gma.c
@@ -113,7 +113,7 @@ static void intel_gma_init(const struct northbridge_intel_x4x_config *info,
 
 	udelay(1);
 
-	intel_gmbus_read_edid(mmio + GMBUS0, 2, 0x50, edid_data,
+	intel_gmbus_read_edid(mmio + GMBUS0, GMBUS_PORT_VGADDC, 0x50, edid_data,
 			sizeof(edid_data));
 	intel_gmbus_stop(mmio + GMBUS0);
 	decode_edid(edid_data,