@@ -122,22 +122,40 @@ 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;
+ bool rc = false;
+ u64 rev;
+ union acpi_object *obj;
+
+ if (!ACPI_HANDLE(&host_bridge->dev))
+ return false;
+
+ /*
+ * 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 check rev 1 first, then rev 2.
+ */
+ for (rev = 1; rev <= 2; rev++) {
+ if (!acpi_check_dsm(ACPI_HANDLE(&host_bridge->dev),
+ &pci_acpi_dsm_guid, rev, BIT(DSM_PCI_PRESERVE_BOOT_CONFIG)))
+ continue;
- /*
- * 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);
+ &pci_acpi_dsm_guid, rev,
+ DSM_PCI_PRESERVE_BOOT_CONFIG,
+ NULL, ACPI_TYPE_INTEGER);
if (obj && obj->integer.value == 0)
- return true;
+ rc = true;
+
ACPI_FREE(obj);
- }
+
+ if (rc)
+ return true;
+ }
return false;
}
Per PCI Firmware Specification Revision 3.3 Table 4-7 _DSM Definitions for PCI. Preserve PCI Boot Configuration Initial Revision ID changed to 2. So add rev2 check and add acpi_check_dsm() for DSM_PCI_PRESERVE_BOOT_CONFIG. Signed-off-by: Zhou Shengqing <zhoushengqing@ttyinfo.com> --- v6:follow Rafael advice, revise code style(use for-loop to check revision). v5:follow Bjorn advice, add acpi_check_dsm for PCI _DSM. 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_re") --- drivers/pci/pci-acpi.c | 42 ++++++++++++++++++++++++++++++------------ 1 file changed, 30 insertions(+), 12 deletions(-)