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4ff116d0d5("PCI/ASPM: Save L1 PM Substates Capability for suspend/resume") restored the L1 PM Substates Capability after resume, which reduced power consumption by making the ASPM L1.x states work after resume.a7152be79b("Revert "PCI/ASPM: Save L1 PM Substates Capability for suspend/resume"") reverted4ff116d0d5because resume failed on some systems, so power consumption after resume increased again.a7152be79bmentioned that we restore L1 PM substate configuration even though ASPM L1 may already be enabled. This is due the fact that the pci_restore_aspm_l1ss_state() was called before pci_restore_pcie_state(). Save and restore the L1 PM Substates Capability, following PCIe r6.1, sec 5.5.4 more closely by: 1) Do not restore ASPM configuration in pci_restore_pcie_state() but do that after PCIe capability is restored in pci_restore_aspm_state() following PCIe r6.1, sec 5.5.4. 2) If BIOS reenables L1SS, particularly L1.2, we need to clear the enables in the right order, downstream before upstream. Defer restoring the L1SS config until we are at the downstream component. Then update the config for both ends of the link in the prescribed order. 3) Program ASPM L1 PM substate configuration before L1 enables. 4) Program ASPM L1 PM substate enables last, after rest of the fields in the capability are programmed. [bhelgaas: commit log, squash L1SS-related patches, do both LNKCTL restores in pci_restore_pcie_state()] Link: https://lore.kernel.org/r/20240128233212.1139663-3-david.e.box@linux.intel.com Link: https://lore.kernel.org/r/20240128233212.1139663-4-david.e.box@linux.intel.com Link: https://lore.kernel.org/r/20240223205851.114931-5-helgaas@kernel.org Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217321 Link: https://bugzilla.kernel.org/show_bug.cgi?id=216782 Link: https://bugzilla.kernel.org/show_bug.cgi?id=216877 Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Co-developed-by: David E. Box <david.e.box@linux.intel.com> Reported-by: Koba Ko <koba.ko@canonical.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: David E. Box <david.e.box@linux.intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Tested-by: Tasev Nikola <tasev.stefanoska@skynet.be> # Asus UX305FA Cc: Mark Enriquez <enriquezmark36@gmail.com> Cc: Thomas Witt <kernel@witt.link> Cc: Werner Sembach <wse@tuxedocomputers.com> Cc: Vidya Sagar <vidyas@nvidia.com>