"proto" overloading in interface configs

[Philip Prindeville]

Hi,

I have a 5G modem (a Quectel RM520N-GL) and it's configured as:

config interface 'qmi'                
        option proto 'qmi'           
        option device '/dev/cdc-wdm0'
        option apn 'b2b.static'      
        option auth 'none'           
        option pdptype 'ipv4'        
        ##option apntype 'default,supl,mms'
        option plmn '310260'               
        option modes '5gnr,lte,umts'       
        option dhcp '1'                    
        option autoconnect '1'    


But I'm confused about the meaning of "proto".  I can mean "none", "static", "dhcp" for what sort of IPv4 allocation is done... but in this case it's "qmi".

What happens when it's a static IPv4 on a modem operating in QMI mode?  How is that expressed?

It seems like we need to different "proto" fields, like an L3 proto and an L2 proto.

Also, what about ECN M or NCM or the other modem modes that aren't QMI or MBIM?

https://openwrt.org/docs/guide-user/network/wan/wwan/ltedongle#about

Those aren't really documented.  My understanding is that the modem I have can do multiple modes, but the other modes aren't documented *and* it's not creating the /dev/ttyUSB0 node that I can pump AT commands into to change its default mode.

philipp at ubuntu24:~/lede$ grep -e mbim -e qmi -e rndis -e ecm -e ncm .config
# CONFIG_PACKAGE_kmod-mhi-wwan-mbim is not set
# CONFIG_PACKAGE_kmod-usb-net-cdc-mbim is not set
# CONFIG_PACKAGE_kmod-usb-net-cdc-ncm is not set
# CONFIG_PACKAGE_kmod-usb-net-huawei-cdc-ncm is not set
# CONFIG_PACKAGE_kmod-usb-net-qmi-wwan is not set
# CONFIG_PACKAGE_kmod-usb-net-rndis is not set
# CONFIG_PACKAGE_libmbim is not set
# CONFIG_PACKAGE_libqmi is not set
# CONFIG_PACKAGE_comgt-ncm is not set
# CONFIG_PACKAGE_umbim is not set
# CONFIG_PACKAGE_uqmi is not set
# CONFIG_PACKAGE_mbim-utils is not set
# CONFIG_PACKAGE_qmi-utils is not set
philipp at ubuntu24:~/lede$ 


So it doesn't feel like it's just a question of missing modules on my install.  I don't even see ECM as being a supported mode.

I'll update the documentation if I can ever get this working, but I don't have high hopes at this point.

I've reached out to Quectel but maybe I should have gotten a Sierra Wireless...

-Philip