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Subject[PATCH V4 11/23] pci, acpi: Move ACPI host bridge device companion assignment to core code.
Currently we have two platforms (x86 & ia64) capable of PCI ACPI host
bridge initialization. They both use sysdata to pass down parent
device reference and both rely on NULL parent in pci_create_root_bus()
to validate sysdata content.

It looks hacky and prevents us from getting some firmware specific
info for PCI host controller e.g. PCI bus domain number.
However, we overcome that blocker by passing down parent
device via pci_create_root_bus parameter (as the ACPI device type)
and using ACPI_COMPANION_SET in core code for ACPI boot method.
ACPI_COMPANION_SET is safe to run for all cases DT, ACPI and DT&ACPI.

Suggested-by: Lorenzo Pieralisi <>
Signed-off-by: Tomasz Nowicki <>
Tested-by: Duc Dang <>
Tested-by: Dongdong Liu <>
Tested-by: Hanjun Guo <>
Tested-by: Graeme Gregory <>
Tested-by: Sinan Kaya <>
drivers/acpi/pci_root.c | 5 ++++-
drivers/pci/probe.c | 2 ++
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ae3fe4e..a65c8c2 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -846,7 +846,10 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,

pci_add_resource(&info->resources, &root->secondary);
- bus = pci_create_root_bus(NULL, busnum, ops->pci_ops,
+ /* Root bridge device needs to be sure of parent ACPI type */
+ ACPI_COMPANION_SET(&device->dev, device);
+ bus = pci_create_root_bus(&device->dev, busnum, ops->pci_ops,
sysdata, &info->resources);
if (!bus)
goto out_release_info;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6d7ab9b..81dd3a2 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2100,6 +2100,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
bridge->dev.parent = parent;
bridge->dev.release = pci_release_host_bridge_dev;
dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
+ ACPI_COMPANION_SET(&bridge->dev,
+ parent ? to_acpi_device_node(parent->fwnode) : NULL);
error = pcibios_root_bridge_prepare(bridge);
if (error) {
 \ /
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