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\r" > /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