ads7648 not work on android

Dear all,
         I use a omap3530 board which contain ads7846 for touch
function. Thouch driver /driver/input/ads7846.c can report message :
ads7846_rx: 63325/63535 118

also report position val in:
static enum hrtimer_restart ads7846_timer(struct hrtimer *handle)
{
  struct ads7846 *ts = container_of(handle, struct ads7846, timer);
  int status = 0;

  spin_lock(&ts->lock);

  if (unlikely(!get_pendown_state(ts) ||
         device_suspended(&ts->spi->dev))) {
    if (ts->pendown) {
      struct input_dev *input = ts->input;

      input_report_key(input, BTN_TOUCH, 0);
      input_report_abs(input, ABS_PRESSURE, 0);
      input_sync(input);

      ts->pendown = 0;
      dev_vdbg(&ts->spi->dev, "UP\n");

UP messaage can output to serial port. However, when I touch the
Android UI, only the ads7846 driver print message, the Android no
response.

I have no idea about the situation, any suggesstion will be apprecate.
Thanks.