[RFC v4 3/7] arm64: PCI: Support root bridge preparation for Hyper-V PCI
From: Boqun Feng <hidden>
Date: 2021-07-14 10:29:41
Also in:
linux-arm-kernel, linux-pci, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
Currently at root bridge preparation, the corresponding ACPI device will be set as the companion, however for a Hyper-V virtual PCI root bridge, there is no corresponding ACPI device, because a Hyper-V virtual PCI root bridge is discovered via VMBus rather than ACPI table. In order to support this, we need to make pcibios_root_bridge_prepare() work with cfg->parent being NULL. Signed-off-by: Boqun Feng <redacted> --- arch/arm64/kernel/pci.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 1006ed2d7c60..3b81ac42bc1f 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c@@ -84,7 +84,13 @@ int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge) { if (!acpi_disabled) { struct pci_config_window *cfg = bridge->bus->sysdata; - struct acpi_device *adev = to_acpi_device(cfg->parent); + /* + * On Hyper-V there is no corresponding APCI device for a root + * bridge, therefore ->parent is set as NULL by the driver. And + * set 'adev` as NULL in this case because there is no proper + * ACPI device. + */ + struct acpi_device *adev = cfg->parent ? to_acpi_device(cfg->parent) : NULL; struct device *bus_dev = &bridge->bus->dev; ACPI_COMPANION_SET(&bridge->dev, adev);
--
2.30.2