Re: [PATCH][upstream] PCI: Add PCI_DEV_FLAGS_USE_NON_MSI_INTX_IRQ to enable non MSI/INTx interrupt

On some platforms, in RC mode, root port has neither MSI/MSI-X nor INTx
interrupt generated, which are available only in EP mode on those platform.
In this case, we try to use other interrupt for port service driver to have
AER, Hot-plug, etc, services to work. (i.e. there is the shared error interrupt
on platform P1010/P3041/P4080 etc)

Signed-off-by: Shengzhou Liu <redacted>
---
 drivers/pci/pcie/portdrv_core.c |   10 ++++++++--
 drivers/pci/quirks.c            |   12 ++++++++++++
 include/linux/pci.h             |    5 +++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 75915b3..837ad15 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c

@@ -212,8 +212,14 @@ static int init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
 	if (!pcie_port_enable_msix(dev, irqs, mask))
 		return 0;
 
-	/* We're not going to use MSI-X, so try MSI and fall back to INTx */
-	if (!pci_enable_msi(dev) || dev->pin)
+	/*
+	 * We're not going to use MSI-X, so try MSI and fall back to INTx.
+	 * Eventually, if neither MSI/MSI-X nor INTx available, try other
+	 * interrupt. (On some platforms, root port doesn't support generating
+	 * MSI/MSI-X/INTx in RC mode)
+	 */
+	if (!pci_enable_msi(dev) || dev->pin || ((dev->dev_flags &
+			PCI_DEV_FLAGS_USE_NON_MSI_INTX_IRQ) && dev->irq))
 		irq = dev->irq;