// wait for DHT to pull pin low.
unit32_t count = 0;
while (pi_2_mmio_input(pin)) {
  if (++count >= DHT_MAXCOUNT) {
  // Timeout waiting for response.
  set_default_priority();
  return DHT_ERROR_TIMEOUT;
  }
}

>>import Adafruit_DHT
>>from Adafruit_DHT import Raspberry_Pi_2_Driver as driver
>>driver.read(2302,4)
(-1,0,0)

>>import Adafruit_DHT
>>Adafruit_DHT.read_retry(2302,4)
Failed to get reading. Try again!

>>sudo ./AdafruitDHT.py 2302 4
Failed to get reading. Try again!