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PCI/MSI: Let PCI host bridges declare their reliance on MSI domains 

There is a whole class of host bridges that cannot know whether
MSIs will be provided or not, as they rely on other blocks
to provide the MSI functionnality, using MSI domains.  This is
the case for example on systems that use the ARM GIC architecture.

Introduce a new attribute ('msi_domain') indicating that implicit
dependency, and use this property to set the NO_MSI flag when
no MSI domain is found at probe time.

Link: https://lore.kernel.org/r/20210330151145.997953-11-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Marc Zyngier 2021-03-30 16:11:41 +01:00 committed by Lorenzo Pieralisi
parent f8bcf249d9
commit 94e89b1453
2 changed files with 3 additions and 0 deletions
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2
drivers/pci/probe.c
View File

@ -925,6 +925,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
device_enable_async_suspend(bus->bridge);
pci_set_bus_of_node(bus);
pci_set_bus_msi_domain(bus);
if (bridge->msi_domain && !dev_get_msi_domain(&bus->dev))
bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
if (!parent)
set_dev_node(bus->bridge, pcibus_to_node(bus));

1
include/linux/pci.h
View File

@ -550,6 +550,7 @@ struct pci_host_bridge {
unsigned int native_dpc:1; /* OS may use PCIe DPC */
unsigned int preserve_config:1; /* Preserve FW resource setup */
unsigned int size_windows:1; /* Enable root bus sizing */
unsigned int msi_domain:1; /* Bridge wants MSI domain */
/* Resource alignment requirements */
resource_size_t (*align_resource)(struct pci_dev *dev,