[SRU] [L/M/Unstable] [PATCH 0/2] Fix numerous AER related issues

[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/2033025

[Impact]
Numerous issues triggered from AER/DPC services

- When AER is shared with PME, cutting the power off the device can
  trigger AER IRQ. Since AER IRQ is shared with PME, it's treated like a
  wakeup source, preventing the system from entering sleep.

- When system resume from S3, device can reset itself and start sending
  PTM messages, triggering AER and reset the entire hierarchy. Since the
  hardware/firmware starts before software, it's never soon enough to put
  a band-aid from kernel.

- Following above one, device firmware restarts before kernel resume,
  when DPC is triggered then the device is gone without any recovering
  method. We really want to prevent that from happening.

[Fix]
Disable and re-enable AER and DPC services on suspend and resume,
respectively.  Right now the the PCI mailing list doesn't have a
consensus which PCI state (D3hot vs D3cold) should the AER/DPC services
should be disabled, so re-instate the old workaround for now.

[Test]
One the workaround is applied, symptoms described above can no longer be
observed.

[Where problems could occur]
Theoretically there can be some "real" issues get unnoticed once AER
gets temporarily disabled, but the benefit far outweighs the downside.

Kai-Heng Feng (2):
  UBUNTU: SAUCE: PCI/AER: Disable AER service during suspend, again
  UBUNTU: SAUCE: PCI/DPC: Disable DPC service during suspend, again

 drivers/pci/pcie/aer.c | 18 ++++++++++++++++
 drivers/pci/pcie/dpc.c | 49 ++++++++++++++++++++++++++++++++----------
 2 files changed, 56 insertions(+), 11 deletions(-)

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2.34.1