diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 65a7da694ef6..4367ecfab2b3 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7978,6 +7978,14 @@ enum drm_mode_status intel_mode_valid(struct drm_device *dev,
 	    mode->vtotal > vtotal_max)
 		return MODE_V_ILLEGAL;
 
+	/*
+	 * WM_LINETIME only goes up to (almost) 64 usec, and also
+	 * knowing that the linetime is always bounded will ease the
+	 * mind during various calculations.
+	 */
+	if (DIV_ROUND_UP(mode->htotal * 1000, mode->clock) > 64)
+		return MODE_H_ILLEGAL;
+
 	return MODE_OK;
 }