diff --git a/drivers/gpu/drm/radeon/rs690.c b/drivers/gpu/drm/radeon/rs690.c
index 1c56062..c065556d 100644
--- a/drivers/gpu/drm/radeon/rs690.c
+++ b/drivers/gpu/drm/radeon/rs690.c
@@ -161,6 +161,11 @@ static void rs690_mc_init(struct radeon_device *rdev)
 	rdev->mc.visible_vram_size = rdev->mc.aper_size;
 	base = RREG32_MC(R_000100_MCCFG_FB_LOCATION);
 	base = G_000100_MC_FB_START(base) << 16;
+	if (rdev->mc.real_vram_size == (384 * 1024 * 1024)) {
+		base += 128 * 1024 * 1024;
+		rdev->mc.real_vram_size -= 128 * 1024 * 1024;
+		rdev->mc.mc_vram_size = rdev->mc.real_vram_size;
+	}
 	rdev->mc.igp_sideport_enabled = radeon_atombios_sideport_present(rdev);
 
 	/* Use K8 direct mapping for fast fb access. */