[PATCH 0/2] PCI: Allow disabling port services on broken root ports

[Han Gao]

Some PCIe root ports break MSI delivery to downstream devices when
native port services (AER, PME, bwctrl, etc.) are active. The existing
pcie_ports=compat kernel parameter works around this globally, but
affects all ports on the system.

This series adds a per-device mechanism to skip port service probing:
  1. Introduce PCI_DEV_FLAGS_NO_PORT_SERVICES flag and wire it into
     the PCIe port driver
  2. Apply it via quirk to Sophgo SG2042 root ports [1f1c:2042], which
     fail to deliver MSI interrupts when port services are enabled

SG2042's PCIe root ports only support MSI, not MSI-X. The MSI
controller provides only 32 vectors shared across all devices behind
each root port. When native port services claim vectors from this
limited pool, downstream devices are starved of interrupts, resulting
in zero interrupts delivered and driver timeouts (e.g. amdgpu fence
fallback timer expired on all rings).

Han Gao (2):
  PCI: Add per-device flag to disable native PCIe port services
  PCI: Add quirk to disable PCIe port services on Sophgo SG2042

 drivers/pci/pcie/portdrv.c |  3 +++
 drivers/pci/quirks.c       | 12 ++++++++++++
 include/linux/pci.h        |  2 ++
 include/linux/pci_ids.h    |  2 ++
 4 files changed, 19 insertions(+)

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2.47.3