[PATCH] unstable/drm-lease: DRM lease protocol support

Philipp Zabel p.zabel at pengutronix.de
Fri Jun 28 12:43:20 UTC 2019

Hi Pekka,

On Fri, 2019-06-28 at 12:58 +0300, Pekka Paalanen wrote:
> On Fri, 28 Jun 2019 11:23:53 +0200
> Philipp Zabel <p.zabel at pengutronix.de> wrote:
> > On Thu, 2019-06-27 at 20:36 +0000, Simon Ser wrote:
> > > What would be other use-cases for DRM leases? Probably fullscreen games?  
> > 
> > One use case I'd like would be presentation software, where tagging the
> > projector as non-desktop beforehand would avoid spilling the desktop
> > onto the presentation display upon connection, before the presentation
> > is started.
> Hi,
> I don't think that is a good idea. Presentation software (Libreoffice,
> web browsers, Evince, ...) probably does not want to grow a whole DRM
> KMS backend just to be able to drive a projector.
> It would be much better for compositors to handle presentation outputs
> specially on their own to not extend the normal desktop contents there,
> and have a simple dedicated extension for presentation software to put
> a wl_surface on a presentation output (if necessary, maybe xdg_output
> and fullscreening to a specific wl_output is already enough).
> There are much more categories of outputs than just "desktop" and
> "non-desktop". I would avoid extending and confusing the meaning of
> "non-desktop" from what it currently is in the Linux kernel.
> Personally I am sceptical that even non-VR games would really benefit
> from DRM leases, because games might want to switch between windowed and
> fullscreen, users might want to see desktop notifications sometimes,
> etc. and again the DRM KMS backend is not easy to write.
> VR apps at least can rely on a VR runtime that knows how to drive DRM
> KMS properly, and there the use of DRM leases is well justified.

I can't argue with this, all of it makes sense.

Another possible use case could be applications for special purpose
displays like the Looking Glass lenticular displays, or anything that we
know for sure the Wayland compositor or normal Desktop applications
won't be able to produce meaningful content for.


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