RS485 on 9G20

I have a strange problem with RS-485.

I compiled the kernel (2.6.30) setting the USART3 following the indications on http://glomation.net/smf/index.php/topic,175.0.html but since I have a 9G20, I put it on the board-sam9g20ek.c file instead of board-sam9260ek.c

The kernel loads ok and shows the four serial ports. Then I run the devmem2 command, but I can't make any connection to ttyS4 and my RS-485 device. On the other hand, when I load the kernel compiled by Glomation I can use the serial port without any problem.

It seems that I have some differences with the Glomation's kernel. Is there any other way to make sure the port is available ? Something to configure in the kernel ? Or the .c file ?

I modified the machine name in MACHINE_START just to make sure that it is indeed compiled.

Attached are my board-sam9g20ek.c , .config.

thanks

Alejandro