linux - How to find the port (/dev/smdX) to which the AT commands should be sent?

Question

I've been using the following format for sending AT commands from the Application processor (AP) to the modem subsystem:

cat /dev/smd7 &
echo -e "ati
" > /dev/smd7

It has always worked but I never realized where's /dev/smd7 port coming from. After looking up online, looks like it's referring to the port used by Radio Interface Layer (RIL), but how does one confirm it?

I have lately started getting timeout issues and I'm starting to wonder if the port may be incorrect or might have changed

read error: Network dropped connection on reset

Note that AP is running linux

Edit: Looks like the modem keeps rebooting hence the read error. But it seems to happen after running the two commands above

question from:https://stackoverflow.com/questions/65839975/how-to-find-the-port-dev-smdx-to-which-the-at-commands-should-be-sent

Answer 1

Waitting for answers