From: Huacai Chen Date: Fri, 30 May 2025 13:45:48 +0000 (+0800) Subject: LoongArch: Preserve firmware configuration when desired X-Git-Tag: v6.16-rc1~12^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=712e6a914328e9672d534fc77edd596234ec2d7f;p=thirdparty%2Flinux.git LoongArch: Preserve firmware configuration when desired If we must preserve the firmware resource assignments, claim the existing resources rather than reassigning everything. According to PCI Firmware Specification: if ACPI DSM#5 function returns 0, the OS must retain the resource allocation for PCI in the firmware; if ACPI DSM#5 function returns 1, the OS can ignore the resource allocation for PCI and reallocate it. Signed-off-by: Qihang Gao Signed-off-by: Juxin Gao Signed-off-by: Huacai Chen --- diff --git a/arch/loongarch/pci/acpi.c b/arch/loongarch/pci/acpi.c index 1da4dc46df43e..50c9016641a48 100644 --- a/arch/loongarch/pci/acpi.c +++ b/arch/loongarch/pci/acpi.c @@ -194,6 +194,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) { struct pci_bus *bus; struct pci_root_info *info; + struct pci_host_bridge *host; struct acpi_pci_root_ops *root_ops; int domain = root->segment; int busnum = root->secondary.start; @@ -237,8 +238,17 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) return NULL; } - pci_bus_size_bridges(bus); - pci_bus_assign_resources(bus); + /* If we must preserve the resource configuration, claim now */ + host = pci_find_host_bridge(bus); + if (host->preserve_config) + pci_bus_claim_resources(bus); + + /* + * Assign whatever was left unassigned. If we didn't claim above, + * this will reassign everything. + */ + pci_assign_unassigned_root_bus_resources(bus); + list_for_each_entry(child, &bus->children, node) pcie_bus_configure_settings(child); }