On Wed, Oct 10, 2018 at 11:58:40AM +0000, Woodhouse, David wrote: > On Wed, 2018-10-10 at 12:27 +0100, Mark Brown wrote: > > If this is a modified IP with additional features then it should be > > given a new compatible string rather than having a property - it's not > > just configuration of the existing IP, it's a new thing and we may find > > there are other quirks that have to be taken care of for it. > No. > It's an extension of the existing IP which is explicitly designed to be > compatible with existing drivers via an opt-in feature. That's totally normal and something that there's already infrastructure to handle, plenty of other IPs have new versions with new features - you can just add a new compatible string and use that to decide which features to enable, and if it's backwards compatible with old versions of the driver supporting older hardware then you can list multiple compatibles. As we just discussed on IRC this is partly a policy thing now I've been told that it's a modified version of the hardware rather than a configuration or integration option, it's easier than having implementations of new features trickle out from the vendor and needing to enable them all one by one in device trees (which does happen). > Which is exactly what we've spent the last decade or two trying to beat > hardware designers into doing, instead of randomly breaking > compatibility for no good reason. That's great and we get to reuse all the driver code with a quirk (a quirk which fixes the hardware to be more compatible with devices, this is a really good hardware change). Ideally we'd be able to enumerate things like IP versions and options from hardware but that's a more entertaining problem. Having said all this if there are production systems using this property, especially production systems where people other than the system integrator can realistically deploy their own kernel separate to the device tree, then supporting those existing DTs even if they're not doing the ideal thing might be the best thing. You mentioned that this might be the case, can you check what the status is there please?
Attachment:
signature.asc
Description: PGP signature
