[RFC v1 0/4] Add support for drivers to decide bridge D3 policy

[Mario Limonciello <mario.limonciello@amd.com>]

The policy for whether PCI bridges are allowed to select D3 is dictated
by empirical results that are enumerated into pci_bridge_d3_possible().

In Windows this behaves differently in that Windows internal policy is
not used for devices when a power engine plugin driver provided by the
SOC vendor is installed.  This driver is used to decide the policy in
those cases.

This series implements a system that lets drivers register such a policy
control as well. It isn't activated for any SOCs by default.

This is heavily leveraged from the work in [1]

[1] https://lore.kernel.org/platform-driver-x86/20230906184354.45846-1-mario.limonciello@amd.com/
Mario Limonciello (4):
  ACPI: x86: s2idle: Export symbol for fetching constraints for module
    use
  PCI: Add support for drivers to decide bridge D3 policy
  PCI: Check for changes in pci_bridge_d3_possible() when updating D3
  platform/x86/amd: pmc: Add support for using constraints to decide D3
    policy

 drivers/acpi/x86/s2idle.c          |   1 +
 drivers/pci/pci.c                  | 148 +++++++++++++++++++++++++++--
 drivers/platform/x86/amd/pmc/pmc.c |  59 ++++++++++++
 include/linux/pci.h                |  54 +++++++++++
 4 files changed, 252 insertions(+), 10 deletions(-)

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2.34.1