The Linux kernel’s Multi-Function Device (MFD) subsystem just got a significant boost for version 7.1. Changes merged this week wire up the Apple SMC power driver to the MFD core. Apple Silicon MacBooks can now report AC status, battery charging, and power metrics directly under the mainline kernel. This lands ahead of the merge window’s close on Sunday.
Phoronix broke the news on April 23, detailing how Hector Martin, known for Asahi Linux work, originally crafted the macsmc-power driver. Refactoring made it upstream-ready, including tweaks for newer SMC firmware. The driver hit the power supply tree last week; now MFD enables it fully. Check the full MFD pull request for details.
MFD handles hardware blocks offering multiple functions—like PMICs mixing regulators, GPIOs, and clocks. A single chip gets parsed into sub-devices. Clean integration matters. Developers avoid reinventing access logic.
This isn’t isolated. The pull adds PCI device IDs for Intel’s Low Power Subsystem on Nova Lake H platforms. Expect better low-power management there. Broader MFD patterns persist: Linux 7.0 brought ROHM BD72720 PMIC, Rockchip RK801, and more via its own MFD updates, per Phoronix coverage from February.
Apple’s Grip Loosens on Linux Hardware Support
Asahi Linux pushes boundaries. Martin’s driver bridges proprietary SMC—System Management Controller—to open code. No more hacks for battery readouts. Users on M-series chips gain reliable metrics. Power tools like TLP or auto-cpufreq will tap this directly.
But challenges remain. SMC firmware evolves; the driver adapts. Upstream demands rigor. Martin’s upstreaming involved code audits, DT bindings, and testing across models. Phoronix notes the power supply merge as a prerequisite—layered commits ensure stability.
Industry watchers see momentum. CNX Software highlighted Arm-side MFD clocks in Linux 7.0, like ExynosAuto v920 support (link). KernelNewbies tracks ongoing MFD expansions (Linux 7.0 page). No fresh X posts on 7.1 MFD surfaced today, but Phoronix forums buzz with Apple enthusiasts.
Wider kernel context? Linux 7.1 merge window hums. USB gains new hardware; PCI adds drivers while dropping relics (Phoronix). NTFS gets a native rewrite for faster Windows volume access (Tom’s Hardware). MFD fits this hardware enablement surge.
For embedded pros, MFD shines in SoCs. Think Rockchip or Qualcomm PMICs—sub-drivers for regulators, LEDs, whatever the chip packs. Intel LPSS extensions hint at x86 efficiency gains. Nova Lake-H? Future laptops, low-power Intel cores.
Developers gain too. MFD cells simplify DT parsing. No more manual platform devices. The pull’s changelog lists DT fixes, regmap tweaks. Stability first.
Apple users rejoice quietly. Mainline Linux on MacBooks inches toward parity. Battery stats were a gap; now filled. Next? Full suspend-resume, fans, sensors. Asahi’s roadmap eyes M3 booting, per related Phoronix pieces.
Kernel maintainers like Lee Jones steward MFD. Pulls like this—timely, tested—keep momentum. Linux 7.1 shapes up stable. Expect RC1 soon post-window.
Hardware vendors take note. Expose multi-function chips via MFD? Upstream fast. Apple’s closed walls crack open. Linux claims more turf.
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