I have an IR port on my laptop. I'm running a kernel; I'd like to
use this IR port to connect to my HP48. Before that, I need to know if the
port works ok.

To test that, I turned on every IR modules in the kernel options
('Networking' section in make menuconfig).

When I modprobe 8250, I see in dmesg

Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing disabled
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

As the laptop doesn't have a physical serial port (DB-9 or DB-25), I guess
it is the IR port.

I also modprobed irtty_sir, and I get this in dmesg:

NET: Registered protocol family 23

so it seems ok.

Next I tried

cat /dev/ttyS0

and I pushed the buttons of my CD player remote in front of the laptop's
diode, but didn't get anything...

How can I be sure that my IR port is set up ok?

Any hint welcome, thanks.