Per PCI Firmware Specification Revision 3.3 Table 4-7 _DSM Definitions
for PCI. Preserve PCI Boot Configuration Initial Revision ID changed to 2.
But the code remains unchanged, still 1.
v4:Initialize *obj to NULL.
v3:try revision id 1 first, then try revision id 2.
v2:add Fixes tag.
Fixes: 9d7d5db8e78e ("PCI: Move PRESERVE_BOOT_CONFIG _DSM evaluation to pci_register_host_bridge()")
Signed-off-by: Zhou Shengqing <zhoushengqing@xxxxxxxxxxx>
---
drivers/pci/pci-acpi.c | 42 ++++++++++++++++++++++++++++++++----------
1 file changed, 32 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index af370628e583..f805cd134019 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -123,19 +123,41 @@ phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
bool pci_acpi_preserve_config(struct pci_host_bridge *host_bridge)
{
if (ACPI_HANDLE(&host_bridge->dev)) {
- union acpi_object *obj;
+ union acpi_object *obj = NULL;
/*
- * Evaluate the "PCI Boot Configuration" _DSM Function. If it
- * exists and returns 0, we must preserve any PCI resource
- * assignments made by firmware for this host bridge.
+ * Per PCI Firmware r3.2, released Jan 26, 2015,
+ * DSM_PCI_PRESERVE_BOOT_CONFIG Revision ID is 1.
+ * But PCI Firmware r3.3, released Jan 20, 2021,
+ * changed sec 4.6.5 to say
+ * "lowest valid Revision ID value: 2". So try revision 1
+ * first for old platform, then try revision 2.
*/
- obj = acpi_evaluate_dsm_typed(ACPI_HANDLE(&host_bridge->dev),
- &pci_acpi_dsm_guid,
- 1, DSM_PCI_PRESERVE_BOOT_CONFIG,
- NULL, ACPI_TYPE_INTEGER);
- if (obj && obj->integer.value == 0)
- return true;
+ if (acpi_check_dsm(ACPI_HANDLE(&host_bridge->dev), &pci_acpi_dsm_guid, 1,
+ 1ULL << DSM_PCI_PRESERVE_BOOT_CONFIG)) {
+ /*
+ * Evaluate the "PCI Boot Configuration" _DSM Function. If it
+ * exists and returns 0, we must preserve any PCI resource
+ * assignments made by firmware for this host bridge.
+ */
+ obj = acpi_evaluate_dsm_typed(ACPI_HANDLE(&host_bridge->dev),
+ &pci_acpi_dsm_guid,
+ 1, DSM_PCI_PRESERVE_BOOT_CONFIG,
+ NULL, ACPI_TYPE_INTEGER);
+ if (obj && obj->integer.value == 0)
+ return true;
+ }
+
+ if (acpi_check_dsm(ACPI_HANDLE(&host_bridge->dev), &pci_acpi_dsm_guid, 2,
+ 1ULL << DSM_PCI_PRESERVE_BOOT_CONFIG)) {
+ obj = acpi_evaluate_dsm_typed(ACPI_HANDLE(&host_bridge->dev),
+ &pci_acpi_dsm_guid,
+ 2, DSM_PCI_PRESERVE_BOOT_CONFIG,
+ NULL, ACPI_TYPE_INTEGER);
+ if (obj && obj->integer.value == 0)
+ return true;
+ }
+
ACPI_FREE(obj);
}
--
2.39.2
