Re: primary device changing from boot to boot

[Dan Williams <dcbw redhat com>]

On Tue, 2017-09-05 at 09:38 -0700, Tim Harvey wrote:
> On Fri, Sep 1, 2017 at 1:22 PM, Dan Williams <dcbw redhat com> wrote:
> > On Fri, 2017-09-01 at 13:01 -0700, Tim Harvey wrote:
> > > Greetings,
> > >
> > > I've got a Sierra Wireless HL7588 modem which exposes three
> > > ttyACM
> > > devs via the cdc_acm driver. The device appears to work fine with
> > > ModemManager (1.6.8) but occasionally mm detects the primary
> > > device
> > > as
> > > ttyACM2 instead of the usuall ttyACM0. In this case (detected
> > > primary
> > > AT interface of ttyACM2), if I've already configured
> > > NetworkManager
> > > to
> > > use /dev/ttyACM0 I can't bring up the modem.
> >
> > NM has a "DeviceIdentifier" property on GSM connections partly for
> > this
> > reason.  You cannot always guarantee that even if MM *did* detect
> > the
> > first exposed TTY as primary, that it's going to be called ttyACM0.
> > The kernel is free to name these things whatever it wants, and if
> > ttyACM0 is already used it'll pick another one.  I've had this
> > happen
> > when some program holds the TTY open and the modem reboots.
> >
> > So moral of the story is, don't depend on device names.
> >
> > Get the MM device identifier from the modem:
> >
> > dbus-send --print-reply --system --
> > dest=org.freedesktop.ModemManager1
> > /org/freedesktop/ModemManager1/Modem/0
> > org.freedesktop.DBus.Properties.Get
> > string:org.freedesktop.ModemManager1.Modem string:DeviceIdentifier
> >
> > and then set that string as the DeviceIdentifier in the
> > NetworkManager
> > connection for the modem.  That connection will then only ever
> > apply to
> > that specific modem.  You can then do things liek "nmcli con up
> > <connection mame>" and NM will figure out what device it should
> > use.
>
> Dan,
>
> This makes sense, but how do I configure NetworkManager to use the
> device-id? I don't see it as an available option for type gsm, so
> perhaps I need to edit the file in
> /etc/NetworkManager/system-connections/mymodem and add it to the
> 'gsm'

nmcli con mod <connection name> gsm.device-id \
    6909b49a4d44867387a2b09b8095c579e031874c

Or yeah, drop:

device-id=6909b49a4d44867387a2b09b8095c579e031874c

into the [gsm] section of the keyfile in /etc/NetworkManager/system-
connections.

> section but maybe I've got larger issues because nm seems to not even
> like ttyACM0 for the interface:
>
> root@ventana:~# mmcli -m 0
>
> /org/freedesktop/ModemManager1/Modem/0 (device id
> '6909b49a4d44867387a2b09b8095c579e031874c')
>   -------------------------
>   Hardware |   manufacturer: 'Sierra Wireless'
>            |          model: 'HL7588'
>            |       revision:
> 'RHL75xx.V.3.7.151600.201702071034.x7160_1'
>            |      supported: 'gsm-umts, lte'
>            |        current: 'gsm-umts, lte'
>            |   equipment id: '014284000070452'
>   -------------------------
>   System   |         device:
> '/sys/devices/soc0/soc/2100000.aips-bus/2184200.usb/ci_hdrc.1/usb2/2-
> 1'
>            |        drivers: 'cdc_acm, cdc_ncm'
>            |         plugin: 'Generic'
>            |   primary port: 'ttyACM0'
>            |          ports: 'wwx000011121314 (net), ttyACM0 (at),
> wwx000011121316 (net), wwx00001112131a (net), wwx000011121318 (net),
> ttyACM2 (at)'
>   -------------------------
>   Numbers  |           own : '+19529136397'
>   -------------------------
>   Status   |           lock: 'none'
>            | unlock retries: 'unknown'
>            |          state: 'enabled'
>            |    power state: 'on'
>            |    access tech: 'unknown'
>            | signal quality: '0' (cached)
>   -------------------------
>   Modes    |      supported: 'allowed: 2g, 3g, 4g; preferred: none'
>            |        current: 'allowed: 2g, 3g, 4g; preferred: none'
>   -------------------------
>   Bands    |      supported: 'unknown'
>            |        current: 'unknown'
>   -------------------------
>   IP       |      supported: 'ipv4, ipv6, ipv4v6'
>   -------------------------
>   3GPP     |           imei: '014284000070452'
>            |  enabled locks: 'none'
>            |    operator id: 'unknown'
>            |  operator name: 'unknown'
>            |   subscription: 'unknown'
>            |   registration: 'idle'
>   -------------------------
>   SIM      |           path: '/org/freedesktop/ModemManager1/SIM/0'
>
>   -------------------------
>   Bearers  |          paths: 'none'
>
> root@ventana:~# dbus-send --print-reply --system \
>    --dest=org.freedesktop.ModemManager1 \
>    /org/freedesktop/ModemManager1/Modem/0 \
>    org.freedesktop.DBus.Properties.Get \
>    string:org.freedesktop.ModemManager1.Modem string:DeviceIdentifier
> method return time=1504629466.392532 sender=:1.3 -> destination=:1.25
> serial=31 reply_serial=2
>    variant       string "6909b49a4d44867387a2b09b8095c579e031874c"
>
> root@ventana:~# nmcli --version
> nmcli tool, version 1.2.6
>
> root@ventana:~# nmcli device status
> DEVICE   TYPE      STATE         CONNECTION
> eth0     ethernet  disconnected  --
> ttyACM0  gsm       unavailable   --
> can0     can       unmanaged     --
> lo       loopback  unmanaged     --

So NM thinks the modem is unavailable.  That's usually caused by
rfkill-switch-type stuff, or because the WWAN plugin hasn't been built
for NM, or it hasn't been built with the right options.

Can you grab NM log output and we can see what's going on?

Also, 'rfkill list' and 'nmcli radio' output.

Dan

> root@ventana:~# nmcli connection add type gsm ifname ttyACM0 con-name
> mymodem apn vzwinternet
> Connection 'mymodem' (ce87bf21-f700-4c61-8165-dda4b6c44ea8)
> successfully added.
>
> nmcli connection add type gsm ifname ttyACM0 con-name mymodem apn
> vzwinternet
>
> root@ventana:~# nmcli connection up mymodem
> Error: Connection activation failed: No suitable device found for
> this
> connection.
> ^^^^^^ not sure why ttyACM0 isn't acceptable here
>
> Thanks,
>
> Tim
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