drm/radeon/kms: fix vram start calculation on ontario (v2)

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 522d29b..f7d7477 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -1134,6 +1134,12 @@
 			rdev->mc.vram_end >> 12);
 	}
 	WREG32(MC_VM_SYSTEM_APERTURE_DEFAULT_ADDR, 0);
+	if (rdev->flags & RADEON_IS_IGP) {
+		tmp = RREG32(MC_FUS_VM_FB_OFFSET) & 0x000FFFFF;
+		tmp |= ((rdev->mc.vram_end >> 20) & 0xF) << 24;
+		tmp |= ((rdev->mc.vram_start >> 20) & 0xF) << 20;
+		WREG32(MC_FUS_VM_FB_OFFSET, tmp);
+	}
 	tmp = ((rdev->mc.vram_end >> 24) & 0xFFFF) << 16;
 	tmp |= ((rdev->mc.vram_start >> 24) & 0xFFFF);
 	WREG32(MC_VM_FB_LOCATION, tmp);