8d95c82f9c
Recent ModemManager versions no longer work on the Samsung A5 (Qualcomm
MSM8916) smartphone: MM ends up in an infinite loop trying to probe the
modem over and over again.
Looking at the debug log it seems to be related to a "Slot Status"
indication that comes in during probe time and causes MM to restart
the probing process:
[/dev/wwan0qmi0] Sent generic request (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Register Events" (0x002E)
<< TLV: translated = physical-slot-status
[/dev/wwan0qmi0] Received generic indication (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Slot Status" (0x0048)
<< TLV: translated = { [0] = '[ physical_card_status = 'present', ...
[/dev/wwan0qmi0] Received generic response (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Register Events" (0x002E)
<< TLV: translated = SUCCESS
[modem42] registered for slot status indications
[/dev/wwan0qmi0] Sent generic request (translated)...
<< QMUX: service = "uim"
<< QMI: message = "Get Slot Status" (0x0047)
[modem42] received slot status indication
[modem42] An active slot had a status change, will reprobe the modem
<infinite loop>
The "Slot Status" indication (uim_slot_status_indication_cb) arrives
immediately after starting to listen for the event, which is before
ModemManager has actually loaded the initial slot status in
uim_get_slot_status_ready. In this situation !slot_array_status_equal()
will always cause the modem to reprobe, even though it is not necessary
during the probe phase.
To fix this add a simple check to uim_slot_status_indication_cb() that
ignores the indication if the initial slot status was not loaded yet.
ModemManager. ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...). Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provide basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it! License. The ModemManager and mmcli binaries are both GPLv2+. The libmm-glib library is LGPLv2+. Code of Conduct. Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms, which you can find in the following link: https://www.freedesktop.org/wiki/CodeOfConduct CoC issues may be raised to the project maintainers at the following address: modemmanager-devel-owner@lists.freedesktop.org