diff options
| -rw-r--r-- | drivers/acpi/property.c | 46 |
1 files changed, 44 insertions, 2 deletions
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c index 5b7c10a2824d..f4776a4085e0 100644 --- a/drivers/acpi/property.c +++ b/drivers/acpi/property.c @@ -108,7 +108,18 @@ static bool acpi_nondev_subnode_extract(union acpi_object *desc, if (handle) acpi_get_parent(handle, &scope); + /* + * Extract properties from the _DSD-equivalent package pointed to by + * desc and use scope (if not NULL) for the completion of relative + * pathname segments. + * + * The extracted properties will be held in the new data node dn. + */ result = acpi_extract_properties(scope, desc, &dn->data); + /* + * Look for subnodes in the _DSD-equivalent package pointed to by desc + * and create child nodes of dn if there are any. + */ if (acpi_enumerate_nondev_subnodes(scope, desc, &dn->data, &dn->fwnode)) result = true; @@ -133,6 +144,12 @@ static bool acpi_nondev_subnode_ok(acpi_handle scope, acpi_handle handle; acpi_status status; + /* + * If the scope is unknown, the _DSD-equivalent package being parsed + * was embedded in an outer _DSD-equivalent package as a result of + * direct evaluation of an object pointed to by a reference. In that + * case, using a pathname as the target object pointer is invalid. + */ if (!scope) return false; @@ -162,6 +179,10 @@ static bool acpi_add_nondev_subnodes(acpi_handle scope, bool ret = false; int i; + /* + * Every element in the links package is expected to represent a link + * to a non-device node in a tree containing device-specific data. + */ for (i = 0; i < links->package.count; i++) { union acpi_object *link, *desc; bool result; @@ -171,17 +192,38 @@ static bool acpi_add_nondev_subnodes(acpi_handle scope, if (link->package.count != 2) continue; - /* The first one must be a string. */ + /* The first one (the key) must be a string. */ if (link->package.elements[0].type != ACPI_TYPE_STRING) continue; - /* The second one may be a string or a package. */ + /* The second one (the target) may be a string or a package. */ switch (link->package.elements[1].type) { case ACPI_TYPE_STRING: + /* + * The string is expected to be a full pathname or a + * pathname segment relative to the given scope. That + * pathname is expected to point to an object returning + * a package that contains _DSD-equivalent information. + */ result = acpi_nondev_subnode_ok(scope, link, list, parent); break; case ACPI_TYPE_PACKAGE: + /* + * This happens when a reference is used in AML to + * point to the target. Since the target is expected + * to be a named object, a reference to it will cause it + * to be avaluated in place and its return package will + * be embedded in the links package at the location of + * the reference. + * + * The target package is expected to contain _DSD- + * equivalent information, but the scope in which it + * is located in the original AML is unknown. Thus + * it cannot contain pathname segments represented as + * strings because there is no way to build full + * pathnames out of them. + */ desc = &link->package.elements[1]; result = acpi_nondev_subnode_extract(desc, NULL, link, list, parent); |