Posted by on Giu 26, 2017 in kernel, Linux, MBIM, ModemManager, Telit | 1 comment

In the past few months a lot of development happened recently in ModemManager, both new features and bugfixings. As usual I will mainly focus on the changes that affect Telit plugin, but I suggest to take a look log at the whole git log since there is a lot more.

Telit plugin in ModemManager

Telit plugin new features

A short list of new features:

Telit plugin bugfixing

Many thanks to Aleksander Morgado and Carlo Lobrano for these!

Concurrent multiple data connections with a single rmnet

Another interesting feature landed recently to the Linux kernel and ModemManager, is related to Qualcomm modems that present a single rmnet device in the USB composition.

I’m experiencing a lot of requests for concurrent data connections due to carrier requirements: mbim based devices are already capable of doing so, since this kind of feature is codified in the standard and implemented in Linux kernel driver (see this Bjorn Mork’s interesting post), while in the past QC modems for this feature relied on distinguished rmnet devices at the usb level.

Current QC chipsets support the multiplexing of an rmnet device, in order to fulfill the requirement: thanks mainly to Bjorn Mork there is now support for this (data part) in Linux qmi_wwan driver, see:

On the user-space side Carlo Lobrano implemented the needed QMI requests:

By the way, it seems that Qualcomm is doing an effort to improve its Linux support for this kind of devices, by submitting patches to the kernel (see drivers: net: Add support for rmnet driver).