The PCI pull request for the Linux 3.9 kernel
reveals that more hot-plugging work is about to land plus developers are still working on the handling of PCI Express ASPM (Active State Power Management), the cause of the major Linux kernel power regression
Bjorn Helgaas sent in the PCI changes for Linux 3.9 on Saturday afternoon. PCI changes for this next kernel include improved major work on host bridge hot-plug with overhauling PCI/ACPI binding, ACPI host-bridge add/start, and other areas. PCI device hot-plugging also saw changes plus there were various other random changes to the Linux PCI sub-system.
When it comes to PCI power management on Linux 3.9, PCI Express Active State Power Management (PCI-E ASPM) will now not be touched by the kernel if it's disabled. There's also a reported fix to the ASPM link state management.
More details on the PCI subsystem changes for the Linux 3.9 kernel can be found from Bjorn's pull request