diff options
Diffstat (limited to 'Documentation/firmware-guide/acpi/dsd/data-node-references.rst')
| -rw-r--r-- | Documentation/firmware-guide/acpi/dsd/data-node-references.rst | 26 |
1 files changed, 12 insertions, 14 deletions
diff --git a/Documentation/firmware-guide/acpi/dsd/data-node-references.rst b/Documentation/firmware-guide/acpi/dsd/data-node-references.rst index 8d8b53e96bcf..ccb4b153e6f2 100644 --- a/Documentation/firmware-guide/acpi/dsd/data-node-references.rst +++ b/Documentation/firmware-guide/acpi/dsd/data-node-references.rst @@ -12,11 +12,14 @@ ACPI in general allows referring to device objects in the tree only. Hierarchical data extension nodes may not be referred to directly, hence this document defines a scheme to implement such references. -A reference consist of the device object name followed by one or more -hierarchical data extension [dsd-guide] keys. Specifically, the hierarchical -data extension node which is referred to by the key shall lie directly under -the parent object i.e. either the device object or another hierarchical data -extension node. +A reference to a _DSD hierarchical data node is a string consisting of a +device object reference followed by a dot (".") and a relative path to a data +node object. Do not use non-string references as this will produce a copy of +the hierarchical data node, not a reference! + +The hierarchical data extension node which is referred to shall be located +directly under its parent object i.e. either the device object or another +hierarchical data extension node [dsd-guide]. The keys in the hierarchical data nodes shall consist of the name of the node, "@" character and the number of the node in hexadecimal notation (without pre- @@ -33,11 +36,9 @@ extension key. Example ======= -In the ASL snippet below, the "reference" _DSD property contains a -device object reference to DEV0 and under that device object, a -hierarchical data extension key "node@1" referring to the NOD1 object -and lastly, a hierarchical data extension key "anothernode" referring to -the ANOD object which is also the final target node of the reference. +In the ASL snippet below, the "reference" _DSD property contains a string +reference to a hierarchical data extension node ANOD under DEV0 under the parent +of DEV1. ANOD is also the final target node of the reference. :: Device (DEV0) @@ -76,10 +77,7 @@ the ANOD object which is also the final target node of the reference. Name (_DSD, Package () { ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), Package () { - Package () { - "reference", Package () { - ^DEV0, "node@1", "anothernode" - } + Package () { "reference", "^DEV0.ANOD" } }, } }) |