are v4l subdevices allowed to not return any available framesizes for the format that's currently active or is it a bug? there are different opinions on whether or not frame size enumeration should be implemented for different classes of subdevs I take it I should just try and see if it works the docs definitely need to make a note on that. If the call didn't succeed on another device I'd be tearing my hair out because the error code indicates invalid params patches are welcome :-) I'm a bit demotivated about sending patches to the kernel tbh you don't have to contribute patches, it's not a requirement but then it's not very fair to complain that things are bad I'm happy to provide feedback by an issue tracker. Is there one for things like that? At least I wouldn't lose track of what I was trying to contribute no there isn't we have very few V4L2 core developers and we're all overworked any issue tracker would just be a write-only /dev/null we need more reviewers and contributors, not more bug reporters I see. I'd be interested in finding a path forward, but I don't think IRC is the right place for it it's good for this kind of questions, but probably not for sending patches :-)