Serial Port I/O Error on Intel NUC with Debian Wheezy

I have a problem getting Serial Port working on INTEL NUC DE3815TYBE. I have Debian Wheezy installed with kernel 3.16.0-0.bpo.4-amd64.

When I do:

setserial -g /dev/ttyS*

I get:

/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: 16550A, Port: 0x0000, IRQ: 19
/dev/ttyS2, UART: 16550A, Port: 0x0000, IRQ: 19
/dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3

I can connect to ttyS0 - ttyS2 without any problem but ttyS3 is not working and I am getting this error:

I call command:

stty -F /dev/ttyS3 9600 cs8 cread clocal

I get:

stty: /dev/ttyS3: Input/output error

Any idea how to fix this? I am running the commands as ROOT. I also tried: setserial /dev/ttyS3 irq 3 uart 16550A skip_test but I am getting the same stty: /dev/ttyS3: Input/output error

Output of:

dmesg | grep tty



[    0.000000] console [tty0] enabled
[    0.952559] serial8250: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[    0.953593] 0000:00:1e.3: ttyS1 at MMIO 0xd0810000 (irq = 19, base_baud = 2764800) is a 16550A
[    0.954072] 0000:00:1e.4: ttyS2 at MMIO 0xd080e000 (irq = 19, base_baud = 2764800) is a 16550A
[  27.740208] ttyS2 - failed to request DMA
[  27.746627] ttyS1 - failed to request DMA
[  440.532070] ttyS3: LSR safety check engaged!
[  443.700047] ttyS3: LSR safety check engaged!
[  445.288960] ttyS3: LSR safety check engaged!
[  452.796029] ttyS3: LSR safety check engaged!
[  453.716441] ttyS3: LSR safety check engaged!
[  463.732506] ttyS3: LSR safety check engaged!
[  470.222491] ttyS3: LSR safety check engaged!
[  470.222774] ttyS3: LSR safety check engaged!
[  473.748363] ttyS3: LSR safety check engaged!
[  474.359756] ttyS3: LSR safety check engaged!
[  482.783201] ttyS3: LSR safety check engaged!
[  483.763953] ttyS3: LSR safety check engaged!
[  493.931641] ttyS3: LSR safety check engaged!
[  503.982224] ttyS3: LSR safety check engaged!
[  514.020686] ttyS3: LSR safety check engaged!
[  524.074170] ttyS3: LSR safety check engaged!
[  534.090644] ttyS3: LSR safety check engaged!
[  544.110381] ttyS3: LSR safety check engaged!

lsof /dev/ttyS3 doesn't return anything so it means there is nothing connected to ttyS3 I guess but I am not very skilled with linux so I might be mistaken

Why I can see 4 ttyS* in my Linux but physicaly I have only 2 physical Serial Ports on the board?