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All Sierra devices appear to require short delay after powering up, otherwise subsequent commands may return errors. Older devices need longer so ensure new devices are penalized just for being new. This is the port to git master of the following commit, for which we don't need to do #2: commit 814febe1fd9baacdb33c79f11c140187df36c4f1 Author: Dan Williams <dcbw@redhat.com> Date: Tue Oct 30 16:16:25 2012 -0500 sierra: fix CFUN power up delay handling 1) all Sierra devices appear to require short delay after powering up, otherwise subsequent commands may return errors. Older devices need longer so ensure new devices are penalized just for being new. 2) When the modem is already in full functionality status and no power up command was sent, there's no need to delay, which was happening regardless of what state the modem was already in. Detect whether the power up was actually executed (response and error will be NULL) and only delay if it was executed.
ModemManager. The problem ModemManager tries to solve is to provide a unified high level API for communicating with (mobile broadband) modems. While the basic commands are standardized, the more advanced operations (like signal quality monitoring while connected) varies a lot. Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides DBus API, it is possible to use 'dbus-send' command to control it from the terminal. There's an example program (tests/mm-test.py) that demonstrates the basic API usage. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C. The devices are queried from udev and automatically updated based on hardware events. There's a GInterface (MMModem) that defines the modem interface and any device specific implementation must implement it. There are two generic MMModem implementations to support the basic operations (one for GSM, one for CDMA,) which are common for all cards. 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 MMModem 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's a fully working plugin in the plugins/ directory for Huawei cards that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! API. The 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!