Hi there,
After switching to Manjaro recently, I’m not able to use my 4G/LTE Sierra Wireless MC7455 modem any more.
The device seems to be initialized correctly at boot, but after a moment disappears, some time I can even it inside the Gnome setting Network Manager menu (extract of dmesg) :
…
[ 15.539827] usbcore: registered new interface driver qcserial
[ 15.539865] usbserial: USB Serial support registered for Qualcomm USB modem
[ 15.540114] qcserial 4-1.4:1.0: Qualcomm USB modem converter detected
[ 15.541099] usb 4-1.4: Qualcomm USB modem converter now attached to ttyUSB0
[ 15.541512] qcserial 4-1.4:1.2: Qualcomm USB modem converter detected
[ 15.541711] usb 4-1.4: Qualcomm USB modem converter now attached to ttyUSB1
[ 15.541975] qcserial 4-1.4:1.3: Qualcomm USB modem converter detected
[ 15.542159] usb 4-1.4: Qualcomm USB modem converter now attached to ttyUSB2
[ 15.550766] usbcore: registered new interface driver cdc_wdm
[ 15.557362] qmi_wwan 4-1.4:1.8: cdc-wdm0: USB WDM device
[ 15.558115] qmi_wwan 4-1.4:1.8 wwan0: register ‘qmi_wwan’ at usb-0000:00:1d.0-1.4, WWAN/QMI device, xx:xx:xx:xx:xx:xx (MAC intentionaly removed for the snippet)
[ 15.558208] usbcore: registered new interface driver qmi_wwan
[ 15.572761] qmi_wwan 4-1.4:1.8 wwp0s29u1u4i8: renamed from wwan0
…
[ 18.253134] qmi_wwan 4-1.4:1.8 wwp0s29u1u4i8: Cannot change a running device
…
[ 45.444628] usb 4-1.4: USB disconnect, device number 3
[ 45.444880] qcserial ttyUSB0: Qualcomm USB modem converter now disconnected from ttyUSB0
[ 45.444899] qcserial 4-1.4:1.0: device disconnected
[ 45.445277] qcserial ttyUSB1: Qualcomm USB modem converter now disconnected from ttyUSB1
[ 45.445291] qcserial 4-1.4:1.2: device disconnected
[ 45.445644] qcserial ttyUSB2: Qualcomm USB modem converter now disconnected from ttyUSB2
[ 45.445658] qcserial 4-1.4:1.3: device disconnected
[ 45.445711] qmi_wwan 4-1.4:1.8 wwp0s29u1u4i8: unregister ‘qmi_wwan’ usb-0000:00:1d.0-1.4, WWAN/QMI device
[ 45.546868] usb 4-1.4: new full-speed USB device number 4 using ehci-pci
[ 45.620213] usb 4-1.4: device descriptor read/64, error -32
[ 45.800208] usb 4-1.4: device descriptor read/64, error -32
[ 45.980329] usb 4-1.4: new full-speed USB device number 5 using ehci-pci
[ 46.053548] usb 4-1.4: device descriptor read/64, error -32
[ 46.237086] usb 4-1.4: device descriptor read/64, error -32
[ 46.343908] usb 4-1-port4: attempt power cycle
[ 46.936996] usb 4-1.4: new full-speed USB device number 6 using ehci-pci
[ 47.350229] usb 4-1.4: device not accepting address 6, error -32
[ 47.423575] usb 4-1.4: new full-speed USB device number 7 using ehci-pci
[ 47.836980] usb 4-1.4: device not accepting address 7, error -32
[ 47.837251] usb 4-1-port4: unable to enumerate USB device
…
I tried MBIM & QMI mode changing the behaviour using an Ubuntu 20.04 live CD, but nothing improved.
I’ve been testing with kernel 4.9.x, 5.4.x and 5.9.x, same problem.
During some seconds I can see the USB device, like :
# lsusb
Bus 004 Device 018: ID 1199:9071 Sierra Wireless, Inc. AirPrime MC7455 3G/4G LTE Modem
<…>
I tried to unload modules one by one, then “modprobe” to load them again.
And the /dev/cdc-wdm0 or /dev/ttyUSB* are not present any more.
Nonetheless, I was coming from LinuxMint (Ubuntu 18.04), and it was working fine. I tried Ubuntu 18.04, Ubuntu 20.04 (kernel 5.4), and the device is detected correctly, and I can activate the Network connection without any issue.
I even flashed my MC7455 to latest firmware version in case of, but no luck, same behaviour, works with other distro but not Manjaro.
I’m still struggling after 2 days (not to mentioned being digging posts, blogs, how to, regarding this matter, didn’t find anything related to).
I strongly think the Manjaro release is lacking of something (kernel modules, systemd, …).
Any help would be much appreciated to keep going with my good old X220 Thinkpad everyday work horse.
Thank you