On Wednesday, April 28th, 2021 at 9:44 AM, Pekka Paalanen ppaalanen@gmail.com wrote:
I'm kind of worried whether you can design a description structure that would be good for a long time. That list already looks quite complicated. Add also watch-like devices with circular displays.
Would the kernel itself use this information at all?
fbcon might want to letter-box its output to make sure it's not obscured behind a cut-out area.
If not, is there not a policy that DT is not a userspace configuration store?
You mentioned the panel orientation property, but that is used by the kernel for fbcon or something, is it not? Maybe as the default value for the CRTC rotation property which actually turns the image?
I wonder if fbcon uses it at all. In general CRTC rotation is not well-supported by HW drivers, at least for linear buffers. CRTC rotation is just an optimization.
Assuming that you succeed in describing these non-usable, funny (waterfall edge), funny2 (e.g. behind a shade or filter so visible but not normal), funny3 (e.g. phone button area with maybe tactile markings), and normal areas, how would userspace handle this information?
Funny2 and funny3 are hypothetical but maybe not too far-fetched.
Is there any provision for generic userspace to handle this generically?
I think the main use-case here is make sure there's nothing important being cut out on screen. I agree we still don't know how the hw will evolve and might design an API which is too restricted. But building something that ends up too complicated and too generic wouldn't be great either.