+/*
+ * Try detecting repeating patterns by keeping track of the last 8
+ * intervals, and checking if the standard deviation of that set
+ * of points is below a threshold. If it is... then use the
+ * average of these 8 points as the estimated value.
+ */
+static void detect_repeating_patterns(struct menu_device *data)
+{
+ int i;
+ uint64_t avg = 0;
+ uint64_t stddev = 0; /* contains the square of the std deviation */
+
+ /* first calculate average and standard deviation of the past */
+ for (i = 0; i < INTERVALS; i++)
+ avg += data->intervals[i];
+ avg = avg / INTERVALS;
+
+ /* if the avg is beyond the known next tick, it's worthless */
+ if (avg > data->expected_us)
+ return;
+
+ for (i = 0; i < INTERVALS; i++)
+ stddev += (data->intervals[i] - avg) *
+ (data->intervals[i] - avg);
+
+ stddev = stddev / INTERVALS;
+
+ /*
+ * now.. if stddev is small.. then assume we have a
+ * repeating pattern and predict we keep doing this.
+ */
+
+ if (avg && stddev < STDDEV_THRESH)
+ data->predicted_us = avg;
+}
+