diff --git a/sys/dev/drm/radeon/cypress_dpm.c b/sys/dev/drm/radeon/cypress_dpm.c
--- a/sys/dev/drm/radeon/cypress_dpm.c
+++ b/sys/dev/drm/radeon/cypress_dpm.c
@@ -561,6 +561,8 @@
 			u32 clk_s, clk_v;
 
 			if (!decoded_ref)
+				return -EINVAL;
+			if (!ss.rate)
 				return -EINVAL;
 			clk_s = reference_clock * 5 / (decoded_ref * ss.rate);
 			clk_v = ss.percentage *