target/linux/generic/backport-5.10/821-v5.13-let-pci-host-bridges-declar-their-reliance-on-msi-domains.patch

   1 From 94e89b145371b68fa0ea294855adebcd03e0522e Mon Sep 17 00:00:00 2001
   2 From: Marc Zyngier <maz@kernel.org>
   3 Date: Tue, 30 Mar 2021 16:11:41 +0100
   4 Subject: PCI/MSI: Let PCI host bridges declare their reliance on MSI domains
   5
   6 There is a whole class of host bridges that cannot know whether
   7 MSIs will be provided or not, as they rely on other blocks
   8 to provide the MSI functionnality, using MSI domains.  This is
   9 the case for example on systems that use the ARM GIC architecture.
  10
  11 Introduce a new attribute ('msi_domain') indicating that implicit
  12 dependency, and use this property to set the NO_MSI flag when
  13 no MSI domain is found at probe time.
  14
  15 Link: https://lore.kernel.org/r/20210330151145.997953-11-maz@kernel.org
  16 Signed-off-by: Marc Zyngier <maz@kernel.org>
  17 Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
  18 Acked-by: Bjorn Helgaas <bhelgaas@google.com>
  19 ---
  20  drivers/pci/probe.c | 2 ++
  21  include/linux/pci.h | 1 +
  22  2 files changed, 3 insertions(+)
  23
  24 --- a/drivers/pci/probe.c
  25 +++ b/drivers/pci/probe.c
  26 @@ -925,6 +925,8 @@ static int pci_register_host_bridge(stru
  27         device_enable_async_suspend(bus->bridge);
  28         pci_set_bus_of_node(bus);
  29         pci_set_bus_msi_domain(bus);
  30 +       if (bridge->msi_domain && !dev_get_msi_domain(&bus->dev))
  31 +               bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
  32
  33         if (!parent)
  34                 set_dev_node(bus->bridge, pcibus_to_node(bus));
  35 --- a/include/linux/pci.h
  36 +++ b/include/linux/pci.h
  37 @@ -548,6 +548,7 @@ struct pci_host_bridge {
  38         unsigned int    native_dpc:1;           /* OS may use PCIe DPC */
  39         unsigned int    preserve_config:1;      /* Preserve FW resource setup */
  40         unsigned int    size_windows:1;         /* Enable root bus sizing */
  41 +       unsigned int    msi_domain:1;           /* Bridge wants MSI domain */
  42
  43         /* Resource alignment requirements */
  44         resource_size_t (*align_resource)(struct pci_dev *dev,