Sakari Ailus of Intel posted a patch to the Linux-ACPI list that enables ‘ACPI graph support’. Slightly edited version of announcement below:
I posted a previous RFC labelled set of ACPI graph support a while ago. Since then, the matter of how the properties should be used as in ACPI _DSD was discussed in Ksummit and LPC, and a document detailing the rules was written . I’ve additionally posted v1 which can be found here. This set contains patches written by Mika Westerberg and by myself. The patchset brings support for graphs to ACPI. The functionality achieved by these patches is very similar to what the Device tree provides: the port and the endpoint concept are being employed. The patches make use of the _DSD property and data extensions to achieve this. The fwnode interface is extended by graph functionality; this way graph information originating from both OF and ACPI may be accessed using the same interface, without being aware of the underlying firmware interface. The last patch of the set contains ASL documentation including an example. The entire set may also be found here (on mediatree.git master, but it also applies cleanly on linux-next). The resulting fwnode graph interface has been tested using V4L2 async with fwnode matching and smiapp and omap3isp drivers, with appropriate changes to make use of the fwnode interface in drivers. The V4L2 patches can be found here. The fwnode graph interface is used by the newly added V4L2 fwnode framework which replaces the V4L2 OF framework, with equivalent functionality.