diff --git a/drivers/gpu/drm/radeon/rv770_dpm.c b/drivers/gpu/drm/radeon/rv770_dpm.c
index cb730cddfb9a..80c595aba359 100644
--- a/drivers/gpu/drm/radeon/rv770_dpm.c
+++ b/drivers/gpu/drm/radeon/rv770_dpm.c
@@ -2536,6 +2536,12 @@ bool rv770_dpm_vblank_too_short(struct radeon_device *rdev)
 	    (rdev->pdev->subsystem_device == 0x1c42))
 		switch_limit = 200;
 
+	/* RV770 */
+	/* mclk switching doesn't seem to work reliably on desktop RV770s */
+	if ((rdev->family == CHIP_RV770) &&
+	    !(rdev->flags & RADEON_IS_MOBILITY))
+		switch_limit = 0xffffffff; /* disable mclk switching */
+
 	if (vblank_time < switch_limit)
 		return true;
 	else