[PATCH 08/13] PCI: MSI: Let PCI host bridges declare their lack of MSI handling

Marc Zyngier
2021-02-25T15:13:07Z

From: Thomas Gleixner <tglx@linutronix.de>

Some PCI host bridges cannot deal with MSIs at all. This has
the unfortunate effect of triggering ugly warnings when an end-point
driver requests MSIs.

Instead, let the bridge advertise such lack of MSIs, so that it
can be flagged correctly by the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
drivers/pci/probe.c | 2 ++
include/linux/pci.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index fb04fc81a8bd..146bd85c037e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -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->no_msi)
+ bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;

if (!parent)
set_dev_node(bus->bridge, pcibus_to_node(bus));
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 105ef1a5191e..9db3abf9fd90 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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 no_msi:1; /* Bridge has no MSI support */

/* Resource alignment requirements */
resource_size_t (*align_resource)(struct pci_dev *dev,
--
2.29.2