ACPICA: Workaround for reversed _PRT entries from BIOS

Some BIOSs erroneously reverse the _PRT SourceName and the
SourceIndex.  Detect and repair this problem. MS ACPI also allows
and repairs this problem, thus ACPICA must also.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/acpi/resources/rscreate.c b/drivers/acpi/resources/rscreate.c
index faddaee1bc07..70c84ece87f1 100644
--- a/drivers/acpi/resources/rscreate.c
+++ b/drivers/acpi/resources/rscreate.c
@@ -285,6 +285,23 @@ acpi_rs_create_pci_routing_table(union acpi_operand_object *package_object,
                 }
 
                 /*
+                 * If the BIOS has erroneously reversed the _PRT source_name (index 2)
+                 * and the source_index (index 3), fix it. _PRT is important enough to
+                 * workaround this BIOS error. This also provides compatibility with
+                 * other ACPI implementations.
+                 */
+                obj_desc = sub_object_list[3];
+                if (!obj_desc
+                    || (ACPI_GET_OBJECT_TYPE(obj_desc) != ACPI_TYPE_INTEGER)) {
+                        sub_object_list[3] = sub_object_list[2];
+                        sub_object_list[2] = obj_desc;
+
+                        ACPI_WARNING((AE_INFO,
+                                      "(PRT[%X].Source) SourceName and SourceIndex are reversed, fixed",
+                                      index));
+                }
+
+                /*
                  * 3) Third subobject: Dereference the PRT.source_name
                  * The name may be unresolved (slack mode), so allow a null object
                  */