FB_SIS=m, DRM_SIS=y is not a legal configuration.

Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/Kconfig

@@ -87,6 +87,7 @@ config DRM_MGA
 config DRM_SIS
 	tristate "SiS video cards"
 	depends on DRM && AGP
+	depends on FB_SIS || FB_SIS=n
 	help
 	  Choose this option if you have a SiS 630 or compatible video
           chipset. If M is selected the module will be called sis. AGP