diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -902,9 +902,17 @@ void intel_dsb_wait_for_delayed_vblank(struct intel_atomic_state *state,
 		 * the hardware itself guarantees that we're SCL lines
 		 * away from the delayed vblank, and we won't be inside
 		 * the vmin safe window so this extra wait does nothing.
+		 *
+		 * Experimentally, DSB may observe a slightly stale
+		 * PIPEDSL value. When the actual scanline has just reached
+		 * safe_window_start, WAIT_DSL_OUT may complete immediately
+		 * due to the stale value.
+		 *
+		 * Shift the start back by one scanline to ensure the wait
+		 * window is entered reliably.
 		 */
 		intel_dsb_wait_scanline_out(state, dsb,
-					    intel_vrr_safe_window_start(crtc_state),
+					    intel_vrr_safe_window_start(crtc_state) - 1,
 					    intel_vrr_vmin_safe_window_end(crtc_state));
 		/*
 		 * When the push is sent during vblank it will trigger