Firewire IEEE-1394 Support Continues To Be Improved With The Linux 6.10 Kernel

While most of you have not thought about or used Firewire (IEEE-1394) in years, there still are some legacy digital video cameras and some professional audio devices relying on the interface. Last year saw a new Firewire maintainer step-up for the Linux kernel after the code had fallen dormant. The plans by that new maintainer, Takashi Sakamoto, are to maintain Linux's Firewire support through 2029. He's continuing to do a good job with the upcoming Linux 6.10 kernel bringing the latest batch of Firewire enhancements.

Takashi Sakamoto sent out the Firewire updates for Linux 6.10 on Tuesday. There's a surprising amount of code churn with legacy interfaces continuing to be updated and discovering other improvements to make. Takashi explained in the pull request:

"During the development period of v6.8 kernel, it became evident that there was a lack of helper utilities to trace the initial state of bus, while investigating certain PHYs compliant with different versions of IEEE 1394 specification.

This series of changes includes the addition of tracepoints events, provided by 'firewire' subsystem. These events enable tracing of how firewire core functions during bus reset and asynchronous communication over IEEE 1394 bus.

When implementing the tracepoints events, it was found that the existing serialization and deserialization helpers for several types of asynchronous packets are scattered across both firewire-core and firewire-ohci kernel modules. A set of inline functions is newly added to address it, along with some KUnit tests, serving as the foundation for the tracepoints events. This renders the dispersed code obsolete.

The remaining changes constitute the final steps in phasing out the usage of deprecated PCI MSI APIs, in continuation from the previous version."

The Linux Firewire support is alive and well in 2024 with more improvements continuing to be made thanks to this maintainer.