[SRU] [G/Unstable/OEM-5.6] [PATCH 0/1] Enable LTR for endpoints behind VMD

[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/1896598

[Impact]
PCIe links behind VMD may not be able to reach ASPM L1.2, because PCIe
Link Tolenrence Reporting doesn't get programmed with a sensible value.

[Fix]
Temporarily hardcode LTR value, which is used by Windows, for NVMe
devices behind VMD.

[Test]
With the patch applied, PCIe links can reach ASPM L1.2, hence the entire
Intel SoC can reach deeper power saving state.

[Regression Potential]
This patch targets specifically Intel Tigerlake VMD bridges, so there
won't be any regression since they are not on the market yet.

Kai-Heng Feng (1):
  UBUNTU: SAUCE: PCI/ASPM: Enable LTR for endpoints behind VMD

 drivers/pci/quirks.c | 49 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 4 deletions(-)

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2.17.1