From a user-space point-of-view, this looks super useful! The uAPI sounds
good to me.
Acked-by: Simon Ser contact@emersion.fr
Would be nice to have some short docs as well. Here's an example of a patch adding some docs for an ioctl [1], if you aren't familiar with that. I think just some basic stuff (description, which parameters are in/out, what the flags are) would be great.