Comment 40 for bug 1348890

Yes, when I looked at it I came to a similar conclusion. From my understanding, what would need to be done is essentially having i915 keep a mapping of it's connectors to the ACPI device id's that are returned via the _ADR method. The only way I know how to do that is to decode them according to the opregion spec, but it does seem to be possible. Once that mapping is created, i915 could set CADL whenever the display switches to a new connector.

The shortcut is to just quirk this somehow, but that doesn't sound like a good overall solution.