Currently, at probing time, the MSI domains of root buses are populated
if either the information of MSI domain is available from firmware (DT
or ACPI), or arch-specific sysdata is used to pass the fwnode of the MSI
domain. These two conditions don't cover all, e.g. Hyper-V virtual PCI
on ARM64, which doesn't have the MSI information in the firmware and
couldn't use arch-specific sysdata because running on an architecture
with PCI_DOMAINS_GENERIC=y.
To support populating MSI domains of the root buses at the probing when
neither of the above condition is true, the ->msi_domain of the
corresponding bridge device is used: in pci_host_bridge_msi_domain(),
which should return the MSI domain of the root bus, the ->msi_domain of
the corresponding bridge is fetched first as a potential value of the
MSI domain of the root bus.
In order to use the approach to populate MSI domains, the driver needs
to dev_set_msi_domain() on the bridge before calling
pci_register_host_bridge(), and makes sure GENERIC_MSI_IRQ_DOMAIN=y.
Another advantage of this new approach is providing an arch-independent
way to populate MSI domains, which allows sharing the driver code as
much as possible between architectures.
Originally-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
drivers/pci/probe.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 60c50d4f156f..ea7f2a57e2f5 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -829,11 +829,15 @@ static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
{
struct irq_domain *d;
+ /* If the host bridge driver sets a MSI domain of the bridge, use it */
+ d = dev_get_msi_domain(bus->bridge);
+
/*
* Any firmware interface that can resolve the msi_domain
* should be called from here.
*/
- d = pci_host_bridge_of_msi_domain(bus);
+ if (!d)
+ d = pci_host_bridge_of_msi_domain(bus);
if (!d)
d = pci_host_bridge_acpi_msi_domain(bus);
--
2.30.2
