On Wed, Jun 20, 2018 at 11:16:15AM -0600, Rob Herring wrote:
Does AC97 specify a common programming model? That's were a common compatible is used (though experience has proven things like "generic-ehci" are don't work).
Yes, there is a standard register interface which all AC'97 CODECs implemented and which does work effectively for drivers that only use that. Devices can offer extensions which do need specific drivers, and there are ID registers which can be used to enumerate. However one of the things that some of the devices targetted at embedded systems do is offer non-standard clocking features that need some configuration during initialization (and may need to work with input clocks too) which complicates things, especially in the context of DT.