modemmanager: apply EPS initial bearer before modem enable

[robimarko]

Maintainer: @feckert
Compile tested: qualcommax/ipq60xx,main
Run tested: qualcommax/ipq60xx,main

Description:
Currently, the EPS initial bearer is getting applied only after the modem has been enabled, but that means that its already registered to the network and might have been using the network provided APN to do so instead of the APN we provided and want to use.

So, in order for the desired APN to always be used to register to the network we need to apply the initial EPS bearer configuration before the modem has been enabled.

[feckert]

That's funny. I was thinking the same thing and have already prepared a patch.
The Problem is, that the modem must be enabled to set the initial bearer.

root@VR2-106149 ~ # mmcli -m Modem1 --3gpp-set-initial-eps-bearer-settings="apn=test.de,allowed-auth=none
,ip-type=ipv4"
error: modem not enabled yet

From my point of view, we can only change this when we have the new ModemManager version 1.24 (which is not released now), as this will probably then be possible. But I still have to verify that. See merged MR

[robimarko]

Ugh, yeah, this works for us in 1.23, to which we had to move since the current stable release cadence is not sufficient.
1.23 has generic AT command support for setting the initial EPS bearer so that is likely why it works for us on RM520N.

The current setting of the initial EPS bearer after modem gets enabled (And thus connects to the network) makes no sense since modem would have already connected with:

1. The old APN it still has hanging around in AT+CGDCONT
2. No APN

So, we had ISP-s complain about this during testing.

As for the MM release cadence, we tried tracking stable releases but they get quite out of date and soon you will need newer features from MM, libqmi, libmbim or else

[feckert]

I have already staged the latest 1.23.11-dev, libqmi and libmbim in my build env. So I can do upstream work for the latest modemmanager master branch. As soon as we have a next modemmanager stable version I will update this in openwrt. I hope this is before we branch to 'openwrt-24.x'.

[robimarko]

Yeah, I have everything updated to latest versions as well as stable is not cutting it.