Installing LTE modem LT4132 (HP EliteBook 830 G5, Fedora 28)

| Why

	LT4132 not working out of the box (august 2018 - Fedora 28, kernel 4.17.17-200)

| How to

1. install Modem Manager

	dnf install modem-manager 
	dnf install modem-manager modem-manager-gui modem-manager-gui-cm-NetworkManager

2. check the integrated USB LTE modem

		T:  Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#=  2 Spd=480 MxCh= 0
		D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=ff MxPS=64 #Cfgs=  3
		P:  Vendor=03f0 ProdID=a31d Rev=01.02
		S:  Manufacturer=HP Inc.
		S:  Product=HP lt4132 LTE/HSPA+ 4G Module
		S:  SerialNumber=......
		C:  #Ifs= 3 Cfg#= 3 Atr=a0 MxPwr=2mA
		I:  If#=0x0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=0e Prot=00 Driver=cdc_mbim
		I:  If#=0x1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim
		I:  If#=0x2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=14 Driver=qcserial
		Bus 001 Device 002: ID 03f0:a31d Hewlett-Packard
	idVendor: 03f0
	idProduct: a31d
	Configuration (Cfg): 3

3. create udev rule /etc/udev/rules.d/99-hp-lt4120.rules

	ACTION!="add|change", GOTO="mbim_to_qmi_rules_end"
	SUBSYSTEM!="usb|drivers", GOTO="mbim_to_qmi_rules_end"

	# load qmi_wwan module
	SUBSYSTEM=="usb", \
	ATTR{idVendor}=="03f0", ATTR{idProduct}=="a31d", \
	RUN+="/sbin/modprobe -b qmi_wwan"

	# force HP lt4132 to configuration #3
	SUBSYSTEM=="usb", \
	ATTR{idVendor}=="03f0", ATTR{idProduct}=="a31d", \

	# add the new id in the qmi_wwan driver
	SUBSYSTEM=="drivers", \
	ENV{DEVPATH}=="/bus/usb/drivers/qmi_wwan", \
	ATTR{new_id}="03f0 a31d"

	# load qcserial module
	SUBSYSTEM=="usb", \
	ATTR{idVendor}=="03f0", ATTR{idProduct}=="a31d", \
	RUN+="/sbin/modprobe -b qcserial"

	# add the new id in the qcserial driver
	SUBSYSTEM=="drivers", \
	ENV{DEVPATH}=="/bus/usb-serial/drivers/qcserial", \
	ATTR{new_id}="03f0 a31d"

4. modify /lib/udev/rules.d/40-usb_modeswitch.rules: add new item/line

	ATTR{idVendor}=="03f0", ATTR{idProduct}=="a31d", RUN+="usb_modeswitch '%b/%k'"

5. reboot the computer for the settings to take effect


After restarting the computer the LTE modem should be accessed via Network Manager or Modem Manager.