Linux power sequencing subsystem (Qualcomm WCN, PCIe M.2, T-Head TH1520)
A generic framework that brings devices up in the correct order of power rails, clocks, and resets, used today for things like Qualcomm Wi-Fi/Bluetooth chips (QCA6390, WCN6750/6855/7850), PCIe M.2 add-in cards on ARM boards, and the GPU on T-Head's TH1520 RISC-V SoC found in boards such as the Lichee Pi 4A.
recommendation
It should stay because this is a young, actively growing subsystem introduced in 2024 to coordinate the order in which power rails, clocks, and resets come up for devices that need a specific bring-up sequence. New providers are still landing in 2025 and 2026 — including support for Qualcomm WCN6855/WCN7850 Wi-Fi/Bluetooth combos, generic PCIe M.2 connectors (with Key E wireless work landing for Linux 7.1), and the T-Head TH1520 GPU used in boards like the Lichee Pi 4A. There is no removal discussion upstream.
repository signals
sources
- git.kernel.org
This directory is a newly added, actively maintained kernel power-sequencing subsystem rather than a legacy orphaned driver.
- git.kernel.org
The Qualcomm provider supports multiple still-relevant wireless PMU compatibles including qcom,qca6390-pmu, qcom,wcn6855-pmu, qcom,wcn7850-pmu, and qcom,wcn6750-pmu.
- git.kernel.org
The PCIe M.2 provider is generic board-level support for DT-described M.2 connectors, a current hardware category rather than a legacy niche.
- git.kernel.org
The TH1520 GPU provider was added for recent T-Head TH1520 platforms, indicating contemporary enablement work.
- lore-kernel.gnuweeb.org
Upstream discussion in 2025 was about adding and integrating TH1520 GPU power sequencing, not removing this subsystem.
- cateee.net
LKDDb shows CONFIG_POWER_SEQUENCING_PCIE_M2 first appearing in 7.0-rc+HEAD, confirming this is very recent upstream functionality.
- wiki.sipeed.com
Commercial TH1520-based Lichee Pi 4A hardware is documented with an online store link, supporting that TH1520 systems remained sold as new hardware into the 2025 era.
- phoronix.com
As of April 13, 2026, pwrseq-pcie-m2 was still gaining new functionality for M.2 Key E wireless connectors, showing active forward development.
codex reasoning notes (technical)
Evidence came from shell inspection of local sources (`rg`, `sed`) and local git history (`git log`) showing 2025-2026 additions/fixes, plus web search results for lore/deployment URLs. No removal discussion was found; the only surfaced thread was an addition/integration series for TH1520 GPU. Because the subsystem was introduced in 2024 and is still gaining providers/features for current DT platforms and M.2 wireless/storage connectors, removal or deprecation is not justified.