i2c_master_send_dmasafe
ret = i2c_master_send_dmasafe(client, (char *)&st->d16, sizeof(st->d16));
ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));