Modem unstable on L5

fch · February 28, 2023, 10:55am

Hello, so I am a new L5 user, a long time pinephone user. I see that the modem is a bit unstable on the L5. So I wonder if Biktorgj’s recommended settings can somehow apply also to the L5.

github.com

the-modem-distro/pinephone_modem_sdk/blob/kirkstone/docs/SETTINGS.md

# Recommended settings
This document describes recommended settings you can apply to your Pinephone or Pinephone Pro to get the best experience out of the modem

## Common
1. If your carrier doesn't provide an alerting tone indication, calls are completely silent until the other party picks up the phone
 - You can enable a local emulation of the alerting tone on the modem, by using the following command (as root): `echo -ne "AT+EN_CAT\r" > /dev/ttyUSB2`

2. If your carrier doesn't provide a valid date and time, the modem will keep looping trying to set the date in the userspace, making all internal generated SMS be sent with an invalid timestamp (2022-01-01).

User @karl implemented a script and a systemd unit that reads the correct date from the Pinephone and sends it via mmcli to the Modem, you can get instructions to set this up [in his blog](https://karl.kashofer.org/pinephone/114)

## Pinephone
1. Frequent disconnects and reconnects (Modem vanishes and reappears a few seconds later during operation or after waking up from suspend)

Sometimes the kernel is too aggressive trying to suspend the USB port when it's actually in use. Disabling runtime suspend for the port usually helps a lot. 
- Edit `/usr/lib/udev/rules.d/80-modem-eg25.rules`
- Look at the first line where it says `ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="2c7c", ATTRS{idProduct}=="0125", ATTR{power/control}="auto"`
- And change it to ON `ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="2c7c", ATTRS{idProduct}=="0125", ATTR{power/control}="on"`

2. Audio volume is too low

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Another thing is how do I update the L5’s firmware and firmware modem? I tried isntalling fwupd, but got no candidates. So I guess fwupd in not on purism repo’s, is that for security reasons?

Captain_Morgan · February 28, 2023, 6:47pm

Thank you for the reference, i have been playing around with suggested settings see below:

https://karl.kashofer.org/pinephone/114 doesn’t seem to exist any longer btw.

Tested except for me it is /dev/ttyUSB3 and doesn’t appear to be a valid command for the Broadmobi BM818 modem. I still don’t get any ring tone.

Tested the following changing:
BM818
85-librem5-pm.rules ATTR{power/control}="on"
85-librem5-pm.rules ATTR{power/autosuspend_delay_ms}="1000"
SD Card
85-librem5-pm.rules ATTR{power/control}="on"
85-librem5-pm.rules ATTR{power/autosuspend_delay_ms}="500"

Observations:

seems to now more reliably re-connect to 4G and Open VPN after waking from suspend, or when toggling HKS
still doesn’t automatically connect on reboot due to Open VPN gnome keyring not unlocking, and hence no Open VPN connection and modem shows with the little ! mark requiring initial mobile data toggle
have not yet seen it randomly disconnect with suspend off, wifi off, camera/microphone off

No idea why that would be though and what the power saving penalty would be when you don’t suspend and just let the phone sit on the desk. Now testing if it still randomly disconnects with suspend off, i have the script package installed that alerts when the modem turns off for some reason and tries to reconnect.

fch · March 3, 2023, 12:34pm

/usr/lib/udev/rules.d/80-modem-eg25.rules

It is empty on mine, should I paste those suggested settings inside it?

dos · March 3, 2023, 12:52pm

PinePhone modem stuff like that is very rarely relevant for Librem 5 and applying some of these tweaks may come with unintended consequences (for example, preventing the hub from being suspended will significantly increase power consumption and generated heat).

fch · March 3, 2023, 1:17pm

Thanks for the info, but is there somthing I can do regarding the modem up’s and down’s? I was thinking of trying mobian and pmOS, to see how it’s working with those OS’es.
I really want to use more the L5, but the pinephone has a modem much more stable atm.

dos · March 3, 2023, 1:34pm

If you don’t care about power consumption and heat, you can disable autosuspend for the hub.

If you do, then - no, not really, except debugging kernel drivers and modem firmware. We’re working on it, but there’s no solution in sight yet.

Captain_Morgan · March 3, 2023, 3:57pm

if you search that directory in the terminal with ls command you should see a librem5-pm.rules entry, which is the one to edit if you want to keep the modem “on”. I think these rules are overwritten on PureOS updating their baseline rules at times. So you almost would want to write a script with all personalizations that you can run after every phone update to make sure certain user settings are honoured.

I think while using the phone with those settings changed maybe it got a little warmer than usual so thats a possible downside, trading stability for battery.