The power sequencing subsystem updates have been merged for the Linux 7.0 cycle. Typically not an area of the kernel too exciting but one new driver addition is the “pwrseq-pcie-m2” to provide power sequencing for PCIe M.2 connectors.
This power sequencing driver for PCIe M.2 connectors is part of the effort for being able to handle PCIe M.2 connectors in Device Tree files. While those on the likes of AMD/Intel x86_64 systems and other ACPI-enabled platforms where the PCIe M.2 interfaces are managed by the firmware/BIOS, for Device Tree platforms the kernel needs to be able to power manage the connectors and associate with Device Tree descriptions.
Linux Device Tree support has lacked proper representation of M.2 connectors and that is finally being addressed with Linux 7.0. The Device Tree binding is merged for Mechanical Key M connectors and this initial enablement is tailored to SSDs via the PCIe interface.
The new driver is gated by the POWER_SEQUENCING_PCIE_M2 Kconfig option for power sequencing of PCIe M.2 connectors exposing interfaces like PCIe, SATA, and UART.
This addition in Linux 7.0 is the main highlight of the power sequencing pull for helping out DT platforms.
