UART Communication not working in Raspberry Pi

```
I am using QExtSerialPort to communicate with the USB seria devices. Now I am 
trying to communicate to a device using UART but its not working I trid the 
latest source code too. 

I tried to communicate using /dev/ttyAMA0

I tested it using uartassistant example. It's failed to open the port.
```

Original issue reported on code.google.com by `arunkuma...@gmail.com` on 25 Jun 2015 at 10:53
