u32 vblank_time = r600_dpm_get_vblank_time(rdev);
u32 switch_limit = pi->mem_gddr5 ? 450 : 300;
+ /* disable mclk switching if the refresh is >120Hz, even if the
+ * blanking period would allow it
+ */
+ if (r600_dpm_get_vrefresh(rdev) > 120)
+ return true;
+
if (vblank_time < switch_limit)
return true;
else