PCI Changes Land In Linux 5.19 - Including Power Management Quirk For Intel DG2 Graphics

The PCI subsystem changes have landed for the in-development Linux 5.19 kernel.

Within the PCI space for Linux 5.19 there are a few items worth mentioning from this feature pull:

- An AMD handling change to only allow D3 if the root port can signal and wake-up from the D3 state. This matches the behavior seen under Microsoft Windows and fixes an issue seen under AMD Yellow Carp to avoid missing hotplug events.

- Linux will now power up devices completely, including anything platform firmware needs to accomplish, during run-time resume. This fixes problems encountered by some in the kernel since a change made in 2018.

- Red Hat's Hans de Goede added new E820 clipping control options and quirks to disable E820 reserved region clipping for various IdeaPads, Yoga, Yoga Slip, Acer Spin 5, Clevo barebones systems, and other devices where clipping leaves no usable address space for touchpads, Thunderbolt devices, and other hardware. The kernel for BIOS years 2023 and beyond will have E820 reserved region clipping disabled by default.

- All Intel Skylake E root ports are now white-listed for peer-to-peer DMA (P2PDMA).

- The previously talked about ASPM / power management quirk for ensuring ASPM can be enabled for Intel DG2/Alchemist graphics cards. This will get ASPM L1 power-savings working on more Intel Arc Graphics hardware.

See this pull for the full list of PCI changes in Linux 5.19.