Function esp_idf_hal::sys::uart_flush_input

pub unsafe extern "C" fn uart_flush_input(uart_num: i32) -> i32

@brief Clear input buffer, discard all the data is in the ring-buffer. @note In order to send all the data in tx FIFO, we can use uart_wait_tx_done function. @param uart_num UART port number, the max port number is (UART_NUM_MAX -1).

@return - ESP_OK Success - ESP_FAIL Parameter error