[OpenWrt-Devel] [ModemManager] How can I make ModemManager work right?

[Alberto Bursi]

On 29/04/20 08:29, Jeonghum Joh wrote:
> Hello,
> Thanks to many people in this list, I was able to find ModemManager and 
> I've tried applying it.
> 
> ==== Testing environment ====
> 
> Target Model        : MediaTek MT7622 AC4300rfb1 board
> Firmware Version : LEDE Reboot 17.01-SNAPSHOT unknown / LuCI
> Kernel Version      : 4.4.124
> Modem                 : HUCOM HM-900
> ModemManager
> Version                 : 1.12.8
> menuconfig          : (QMI on, MBIM off)
> git clone URL        : 
> https://github.com/openwrt/packages/tree/master/net/modemmanager
> 
> Noted Device Files : Those files and paths are noted/watched
> qmichannel                                            : /dev/cdc-wdm0
> usbnet_adapter                                      : /sys/class/net/wwan0
> /sys/bus/usb/devices/2-1/manufacturer : QCOM
> /sys/bus/usb/devices/2-1/idVendor        :05C6
> /sys/bus/usb/devices/2-1/idProduct       :90db
> /sys/bus/usb/devices/2-1/speed             :5000
> /sys/bus/usb/devices/2-1/product          :SDXPRAIRIE-MTP _SN:B02CE51B
> /sys/bus/usb/devices/2-1/version           :3.20
> /sys/bus/usb/devices/2-1:1.2/net/wwan0
> /sys/bus/usb/devices/2-1:1.2/net/wwan0/device/driver
> /sys/bus/usb/devices/2-1:1.2/net/wwan0/device
> /sys/bus/usb/devices/2-1:1.2/usbmisc/cdc-wdm0
> /sys/devices/platform/1a0c0000.usb/usb2/2-1/2-1:1.2
> 
> Kernel modules watched via lsmod
> cdc_wdm                 8821  1 qmi_wwan
> qmi_wwan                6252  0
> usbcore               153512 20 
> option,usb_wwan,qmi_wwan,cdc_ncm,cdc_ether,usbserial,usbnet,usblp,cdc_wdm,cdc_acm,usb_storage,xhci_mtk,xhci_plat_hcd,xhci_pci,xhci_hcd,uhci_hcd,ohci_platform,ohci_hcd,ehci_platform,ehci_hcd
> usbnet                 19027  3 qmi_wwan,cdc_ncm,cdc_ether
> 
> Above is original environment.
> On this circumstances, I disabled CM provided from modem provider : hucom-cm
> And I added one configuration section into the bottom of 
> /etc/config/network :
> config interface 'broadband'
>          option device '/sys/devices/platform/1a0c0000.usb/usb2/2-1/2-1:1.2'
>          option proto 'modemmanager'
>          option apn '5g-internet.sktelecom.com 
> <http://5g-internet.sktelecom.com>'
>          option username ''
>          option password ''
>          option pincode ''
>          option lowpower '1'
> 
> Under these settings, I confirmed that
> - hucom-cm is disabled
> - ModemManager is alive
>   4430 root      229m D    /usr/sbin/ModemManager
> 
> The wwan0 is not shown from ifconfig and ping 8.8.8.8 fails saying 
> Network is unreachable.
> So, My first trying to utilize MM seemed to be failed.
> 
> Originally hucom-cm sets bridge mode like shown below:
> BRIDGE_MODE_FILE : /sys/module/qmi_wwan/parameters/bridge_mode
> BRIDGE_IPV4_FILE    : /sys/module/qmi_wwan/parameters/bridge_ipv4
> But under ModemManager these files are not shown.
> 
> And I've found many plugin libraries under /usr/lib/ModemManager:
> libmm-plugin-altair-lte.so     libmm-plugin-mtk.so           
>   libmm-plugin-thuraya.so
> 
> Could someone help me?
> 
> Do I need to look deeper into ModemManager?
> Do I need to implement new plugin library for our product?
> Or do I need to forget about ModemManager?
> 
> My already given hucom-cm anyway works. It brings data via wwan0 and 
> establish network interface wwan0.
> Problem is that hucom-cm sets up firewall rules and routing settings 
> redundantly and unnecessarily. So I can make it not to do these unneeded 
> settings. This way would be good approach I believe.
> But we'd like to make our product indepecntant from specific modem. I 
> guessed that opensource ModemManager infrastructure would give us some 
> sort of independence from specific modem and in other words it would 
> give some abstraction..
> 
> I am not sure of anything. Could someone give me some light so that I 
> can find the best way to go?
> 
> Additional question : If I write our own logic as a plugin library of 
> ModemManager, wouldn't it necessarily have to stick to GPL? Can we apply 
> commercial license for the plugin?
> 
> Thank you very much in advance.
> Jeonghum

If none answers better in this mailing list, development and licensing 
questions about ModemManager should probably be asked in its own mailing 
list https://lists.freedesktop.org/mailman/listinfo/modemmanager-devel

As it is not a package developed by OpenWrt, it is used by desktop Linux 
distributions too (Ubuntu, RHEL, SUSE and most others), Openwrt only 
provides the package and integrates its config with uci.

-Alberto

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