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LoongArch: Preserve firmware configuration when desired

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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 <gaoqihang@loongson.cn>
Signed-off-by: Juxin Gao <gaojuxin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Huacai Chen
2025-05-30 21:45:48 +08:00
parent 52c22661c7
commit 712e6a9143
1 changed files with 12 additions and 2 deletions
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14
arch/loongarch/pci/acpi.c
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@@ -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);
}