DENT has made significant strides in enhancing the upstream Linux Kernel to function as NoS without additional overheads for retail-edge use cases. A critical feature for these edge scenarios is Power over Ethernet (PoE). In this blog post, we will explore DENT’s contributions by examining past, present, and future PoE support in the upstream Linux Kernel.
Past Developments:
Previously, the Linux kernel offered no support for PoE technologies. Hardware vendors frequently provided non-universal, user-space solutions resulting in fragmented and inconsistent implementations. DENT recognized the need for evolution and began developing a standardized solution integrated within the Linux kernel.
In 2022, a major milestone was reached when a Power Sourcing Equipment (PSE) subsystem was added to the Linux kernel. However, this subsystem was only capable of supporting a related technology called Power over Data-Lines (PoDL). Learning and building from this achievement, DENT focused on implementing total PoE support.
Ongoing Developments:
DENT member Bootlin has spearheaded the development of DENT’s upstreaming efforts. Our initial goal was to bring basic PoE support, focusing on basic features like enabling and disabling power and achieving port status. This successful effort resulted in the development and upstreaming of drivers for two different PoE controllers: Microchip PD692x0 and TI TPS23881.
Bootlin’s Köry Maincent (Embedded Linux and Kernel Engineer) played a critical role in this development, spanning nine iterations from November 2023 to April 2024. The culmination of this work will be seen in the Linux 6.10 release, marking a significant achievement for DENT and the broader Linux community.
For more information on Maincent’s remarkable work, watch his presentation from Embedded Open Source Summit 2024.
Following the initial support, DENT immediately began working on the next set of features, including enhanced status information like consumed power, negotiated class and extended state reports, as well as the option to read and configure PoE port power limits. This work, developed through six iterations, has been merged and is set to be included in Linux 6.11.
What’s Next:
Looking ahead, DENT has ambitious plans for PoE. Next steps include:
- Supporting port priority to manage power allocation when existing, available power is insufficient.
- Implementing the PD62x0 persistent configuration mechanism for custom configurations across reboots.
- Modifying the POED project to use the new standard Linux interface for PoE instead of user-space drivers.
DENT is committed to further enhancing PoE support within the Linux kernel. Stay tuned as DENT continues to build a brighter future for open source PoE.
For more information on Bootlin’s PoE work, read its recent PoE blog: https://bootlin.com/blog/power-over-ethernet-poe-support-into-the-official-linux-kernel/
Check out upcoming events where DENT will be present: https://dent.dev/event/