On Wed, 28 Apr 2021 07:21:28 +0000
Simon Ser <contact@emersion.fr> wrote:

> > A solution to make this configuration generic and exposed by the kernel
> > would standardise this across Linux  
> 
> Having a KMS property for this makes sense to me.
> 
> Chatting with Jani on IRC, it doesn't seem like there's any EDID or
> DisplayID block for this.
> 
> Note, Android exposes a data structure [1] with:
> 
> - Margin of the cut-out for each edge of the screen
> - One rectangle per edge describing the cut-out region
> - Size of the curved area for each edge of a waterfall display
> 
> I haven't found anything describing the rounded corners of the display.
> 
> [1]: https://developer.android.com/reference/android/view/DisplayCutout

Hi,

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?

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?

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?

This seems more like a job for the hypothetical liboutput, just like
recognising HMDs (yes, I know, kernel does that already, but there is a
point that kernel may not want to put fbcon on a HMD).


Thanks,
pq