DRM page-flip with damage for weston

[Deepak Singh Rawat]

> > > The damage region received during output repaint is in Weston's global
> > > co-ordinate space. To shift to CRTC co-ordinates, you need to
> > > translate the damage region by (-output->x, -output->y). When we are
> > > using the renderer, there is no scaling, so CRTC co-ordinates and
> > > framebuffer co-ordinates are guaranteed to be equal. This only
> > > accounts for the primary plane; damage to views on other planes is
> > > considered separately.
> > >
> > > Also, if you are not already working from git master, I recommend you
> > > do so, as the DRM backend has changed hugely since 4.0.0.
> >
> > Thanks Daniel for help and it the change suggested by you are working with
> > my drm code. Another question regarding Weston, does each output in
> > Weston create separate scan-out framebuffer always ?
> 
> No problem - it does always create a separate scanout buffer for
> renderer (GL/etc) buffers. For user buffers which are directly scanned
> out (e.g. fullscreen windows), the user may have specified a viewport
> scale/crop which requires translation, but I don't think this should
> have an effect if the damage region you are after has to be in CRTC
> co-ords.

The damage is a plane property and it is in framebuffer coordinate of the
framebuffer attached to the plane. For now in Weston I only have covered
the first case, will check the case for user buffers which are directly
scanned out. Thanks. 


> 
> Cheers,
> Daniel