Description
The Devicetree Microconference focuses on discussing and solving problems present in the systems using Devicetree as firmware representation. This notably is Linux kernel and U-Boot, which share the Devicetree bindings and sources, but also can cover topics relevant to Zephyr or System Devicetrees. Systems using Devicetree are majority of embedded boards, mobile devices and ARM64 laptops.
Ongoing problems, being discussed last year in LPC 2025 or previous years:
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Status of DTS validation against DT schema among SoC platforms: are we getting to error-free dtbs_check anywhere? What are the blockers in achieving compliance, what is the progress.
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Hot-pluggable hardware with Devicetree overlays (addons) - on-going efforts, discussed also on LPC 2024. Current work includes changing the DTB format (RFC patches posted).
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Sharing DT bindings and DTS sources with U-Boot (aka OF_UPSTREAM): progress and what are the obstacles?
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Shall we migrate all of_property_read_xxx() calls in Linux drivers to device_property_read_xxx() to handle also ACPI?
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Fixing common pattern of unconditional device_init_wakeup() in drivers which makes it impossible to disable it via Devicetree, since wakeup-source is bool.
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Style-checker (aka checkpatch) for DTS - tool automating all style related reviews. Discussed in 2025, but no tool got wide acceptance.
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Power sequencing for enumerable busses - is it done yet? Discussion in 2025 suggested that at least MDIO is suffering from lack of generic solution for power sequencing.
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How to choose and apply overlays, when vendor wants to ship many of them with single image. Many Android builds follow such approach. No generic properties/bindings were accepted so far. Discussed also in 2025.
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DTB selection on EFI systems like arm64 laptops or embedded boards: How to store, update and choose the DTB to pass to the Linux kernel? The problem might be solved by Ubuntu Stubble, so is it considered a community consensus? What is still missing?
Key attendees:
AngeloGioacchino Del Regno, Arnd Bergmann, Bartosz Golaszewski, Bjorn Andersson, Chen-Yu Tsai, Conor Dooley, Douglas Anderson, Geert Uytterhoeven, Hervรฉ Codina, Konrad Dybcio, Luca Ceresoli, Michal Simek, Nishanth Menon, Rob Herring, Saravana Kannan, Thierry Reding, Wolfram Sang
Expected attendees (very likely to come): Arnd Bergmann, Bartosz Golaszewski, Bjorn Andersson, Chen-Yu Tsai, Conor Dooley, Geert Uytterhoeven, Hervรฉ Codina, Konrad Dybcio, Luca Ceresoli, Michal Simek, Wolfram Sang
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Mr Krzysztof Kozlowski (Qualcomm)
The great benefit of Devicetree bindings in the current DT schema format is the ability to validate the correctness of DTS (Devicetree sources) against those bindings. However, once validation was introduced, we discovered that many in-kernel DTS files simply did not pass.
Continuing such summary from 2025, what is the status of dtbs_check now? Which platforms have the most warnings and...
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Doug Anderson
It is commonplace that many boards in the real world have many sibling or cousin boards that are 95-99% the same as each other. Some examples:
- During development, most boards go through several revisions. A board might have proto0, proto1, evt0, evt1, evt1.1, dvt1, pvt, and mp revisions. These revisions almost the same with just small changes. While only "mp" (mass production) devices...
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Neil Armstrong (Linaro)
Since early 2024, U-Boot has been synchronizing the DTS and bindings of each Linux release into the U-Boot source tree using git subtree functionality. Since this transition, some platforms like Amlogic or Qualcomm have immediately switched, and some older platforms have been actively migrating to upstream Linux DT sources and bindings while maintaining minimal local U-Boot DTS...
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Hervรฉ Codina
Device Tree has been extremely successful at describing non-discoverable hardware in Linux and other embedded systems. However, it remains fundamentally monolithic: each Device Tree describes a complete system, and reuse across independently developed hardware components is limited.
This becomes problematic for modular platforms where expansion boards, mezzanines, daughter cards, or...
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