drm/radeon/kms: rs6xx/rs740: clamp vram to aperture size

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rs690.c b/drivers/gpu/drm/radeon/rs690.c
index 81b8efc..30913c3 100644
--- a/drivers/gpu/drm/radeon/rs690.c
+++ b/drivers/gpu/drm/radeon/rs690.c
@@ -134,7 +134,7 @@
 	fixed20_12 a;
 
 	rs400_gart_adjust_size(rdev);
-	/* DDR for all card after R300 & IGP */
+
 	rdev->mc.vram_is_ddr = true;
 	rdev->mc.vram_width = 128;
 
@@ -143,6 +143,13 @@
 
 	rdev->mc.aper_base = drm_get_resource_start(rdev->ddev, 0);
 	rdev->mc.aper_size = drm_get_resource_len(rdev->ddev, 0);
+
+	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;
+
 	rs690_pm_info(rdev);
 	/* FIXME: we should enforce default clock in case GPU is not in
 	 * default setup