MC7455 - /dev/ttyUSB2 is not working

Hello,

I am using MC7455 for my project. I have connected the module through USB to PCIe adapter. On startup I could see that the device is attached to my system.

root@cl-som-imx7:~# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 1199:9071 Sierra Wireless, Inc.

root@cl-som-imx7:~# ls -l /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Sep 7 12:17 /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 1 Sep 7 12:17 /dev/ttyUSB1
crw-rw---- 1 root dialout 188, 2 Sep 7 12:17 /dev/ttyUSB2

and also I have two /cdc/wdm interfaces.

I want to activate the GPS functionalities. So to send the AT commands, I tried opening the interface ttyUSB2 using minicom. The baudrate is 115200.I am seeing the following messages on the terminal:

tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_write - 1 byte(s)
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room
tty ttyUSB2: serial_tiocmget
tty ttyUSB2: serial_ioctl - cmd 0x5401
tty ttyUSB2: serial_chars_in_buffer
tty ttyUSB2: serial_write_room

I tried using other USB interfaces, I am seeing similar messages. Any information on how to fix this will help me.

Linux Kernel Version : 4.9.39

Thanks & Regards,
Vinothkumar

Vino,

Are literally seeing text such as ‘serial_write_room’ come out of minicom from /dev/ttyUSB2? BTW the baud rate does not matter with USB as it automatically adjusts.

Regards

Matt

Oh yeah also make sure modem manager is off as well. That is the only time I have seen AT commands being sent to the unit while I have been in minicom.

Regards

Matt