Commit 94e89b14 authored Mar 30, 2021 by Marc Zyngier Committed by Lorenzo Pieralisi Apr 20, 2021

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>

parent f8bcf249

drivers/pci/probe.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -925,6 +925,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
	device_enable_async_suspend(bus->bridge);		device_enable_async_suspend(bus->bridge);
	pci_set_bus_of_node(bus);		pci_set_bus_of_node(bus);
	pci_set_bus_msi_domain(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)		if (!parent)
	set_dev_node(bus->bridge, pcibus_to_node(bus));		set_dev_node(bus->bridge, pcibus_to_node(bus));

include/linux/pci.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -550,6 +550,7 @@ struct pci_host_bridge {
	unsigned int native_dpc:1; /* OS may use PCIe DPC */		unsigned int native_dpc:1; /* OS may use PCIe DPC */
	unsigned int preserve_config:1; /* Preserve FW resource setup */		unsigned int preserve_config:1; /* Preserve FW resource setup */
	unsigned int size_windows:1; /* Enable root bus sizing */		unsigned int size_windows:1; /* Enable root bus sizing */
			unsigned int msi_domain:1; /* Bridge wants MSI domain */

	/* Resource alignment requirements */		/* Resource alignment requirements */
	resource_size_t (align_resource)(struct pci_dev dev,		resource_size_t (align_resource)(struct pci_dev dev,