+
+ /* Calc recv margin
+ * M: Receive margin (%)
+ * N: Ratio of bit rate to clock (N = sampling rate)
+ * D: Clock duty (D = 0 to 1.0)
+ * L: Frame length (L = 9 to 12)
+ * F: Absolute value of clock frequency deviation
+ *
+ * M = |(0.5 - 1 / 2 * N) - ((L - 0.5) * F) -
+ * (|D - 0.5| / N * (1 + F))|
+ * NOTE: Usually, treat D for 0.5, F is 0 by this
+ * calculation.
+ */
+ recv_margin = abs((500 -
+ DIV_ROUND_CLOSEST(1000, sr << 1)) / 10);