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PCI/DPC: Add "pcie_ports=dpc-native" to allow DPC without AER control

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Prior to eed85ff4c0 ("PCI/DPC: Enable DPC only if AER is available"),
Linux handled DPC events regardless of whether firmware had granted it
ownership of AER or DPC, e.g., via _OSC.

PCIe r5.0, sec 6.2.10, recommends that the OS link control of DPC to
control of AER, so after eed85ff4c0, Linux handles DPC events only if it
has control of AER.

On platforms that do not grant OS control of AER via _OSC, Linux DPC
handling worked before eed85ff4c0 but not after.

To make Linux DPC handling work on those platforms the same way they did
before, add a "pcie_ports=dpc-native" kernel parameter that makes Linux
handle DPC events regardless of whether it has control of AER.

[bhelgaas: commit log, move pcie_ports_dpc_native to drivers/pci/]
Link: https://lore.kernel.org/r/20191023192205.97024-1-olof@lixom.net
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Olof Johansson
2019-10-23 12:22:05 -07:00
committed by Bjorn Helgaas
parent 161eea1b25
commit 35a0b2378c
5 changed files with 19 additions and 2 deletions
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2
Documentation/admin-guide/kernel-parameters.txt
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@@ -3540,6 +3540,8 @@
even if the platform doesn't give the OS permission to
use them. This may cause conflicts if the platform
also tries to use these services.
dpc-native Use native PCIe service for DPC only. May
cause conflicts if firmware uses AER or DPC.
compat Disable native PCIe services (PME, AER, DPC, PCIe
hotplug).