char __user *user_buffer);
size_t iio_dma_buffer_data_available(struct iio_buffer *buffer);
int iio_dma_buffer_set_bytes_per_datum(struct iio_buffer *buffer, size_t bpd);
-int iio_dma_buffer_set_length(struct iio_buffer *buffer, int length);
+int iio_dma_buffer_set_length(struct iio_buffer *buffer, unsigned int length);
int iio_dma_buffer_request_update(struct iio_buffer *buffer);
int iio_dma_buffer_init(struct iio_dma_buffer_queue *queue,