diff --git a/board/google/gru/gru.c b/board/google/gru/gru.c
index b116b1a..c2895e1 100644
--- a/board/google/gru/gru.c
+++ b/board/google/gru/gru.c
@@ -10,7 +10,28 @@
 	return 0;
 }
 
+#ifdef CONFIG_SPL_BUILD
 /* provided to defeat compiler optimisation in board_init_f() */
 void gru_dummy_function(int i)
 {
 }
+
+int board_early_init_f(void)
+{
+# ifdef CONFIG_TARGET_CHROMEBOOK_BOB
+	int sum, i;
+
+	/*
+	 * Add a delay and ensure that the compiler does not optimise this out.
+	 * This is needed since the power rails tail a while to turn on, and
+	 * we get garbage serial output otherwise.
+	 */
+	sum = 0;
+	for (i = 0; i < 150000; i++)
+		sum += i;
+	gru_dummy_function(sum);
+#endif /* CONFIG_TARGET_CHROMEBOOK_BOB */
+
+	return 0;
+}
+#endif