diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 5f42fad..c7233ad 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -380,6 +380,13 @@
 	/* Setup GPU memory space */
 	rdev->mc.mc_vram_size = RREG32(CONFIG_MEMSIZE);
 	rdev->mc.real_vram_size = RREG32(CONFIG_MEMSIZE);
+
+	if (rdev->mc.mc_vram_size > rdev->mc.aper_size)
+		rdev->mc.mc_vram_size = rdev->mc.aper_size;
+
+	if (rdev->mc.real_vram_size > rdev->mc.aper_size)
+		rdev->mc.real_vram_size = rdev->mc.aper_size;
+
 	if (rdev->flags & RADEON_IS_AGP) {
 		r = radeon_agp_init(rdev);
 		if (r)
diff --git a/drivers/gpu/drm/radeon/rv770.c b/drivers/gpu/drm/radeon/rv770.c
index b574c73..efca509 100644
--- a/drivers/gpu/drm/radeon/rv770.c
+++ b/drivers/gpu/drm/radeon/rv770.c
@@ -801,6 +801,13 @@
 	/* Setup GPU memory space */
 	rdev->mc.mc_vram_size = RREG32(CONFIG_MEMSIZE);
 	rdev->mc.real_vram_size = RREG32(CONFIG_MEMSIZE);
+
+	if (rdev->mc.mc_vram_size > rdev->mc.aper_size)
+		rdev->mc.mc_vram_size = rdev->mc.aper_size;
+
+	if (rdev->mc.real_vram_size > rdev->mc.aper_size)
+		rdev->mc.real_vram_size = rdev->mc.aper_size;
+
 	if (rdev->flags & RADEON_IS_AGP) {
 		r = radeon_agp_init(rdev);
 		if (r)