[RFC 1/1] Add color manager calibration protocol v1

[Pekka Paalanen]

On Tue, 16 Apr 2019 15:35:45 +0300
Pekka Paalanen <ppaalanen at gmail.com> wrote:

> On Tue, 16 Apr 2019 13:14:58 +0200
> Erwin Burema <e.burema at gmail.com> wrote:
> 
> > On Tue, 16 Apr 2019 at 12:51, Pekka Paalanen <ppaalanen at gmail.com> wrote:  
> > >
> > > On Sun, 14 Apr 2019 12:57:48 +0200
> > > Erwin Burema <e.burema at gmail.com> wrote:
> > >    
> > > > ---
> > > >  .../cm_wayland_calibration.xml                | 106 ++++++++++++++++++

> > > Hi,
> > >
> > > would you not need a corresponding event to know the compositor has
> > > shown the requested color?
> > >
> > > It could be as simple as a new_id argument with wl_callback interface.
> > >    
> > 
> > Good point, will add that in the next version. Might also be an
> > interesting way to measure GPU/display latency (time from callback
> > received to actual change observed on screen although not sure how
> > accurate that will be)  
> 
> Hi,
> 
> the Wayland presentation-time extension is much better for latency
> measurements as it delivers a flip timestamp hopefully from the
> hardware. You can trivially compute the delay from client update to
> hardware flip, and with a measurement device you can measure from flip
> to light if you can synchronise the clocks.
> 
> But to use that you need a wl_surface.

Wayland presentation-time extension:
https://gitlab.freedesktop.org/wayland/wayland-protocols/blob/master/stable/presentation-time/presentation-time.xml

The relevant event is wp_presentation_feedback.presented.

An example of a calibration extension that hijacks a whole output (and
a specific input device) is here:
https://gitlab.freedesktop.org/wayland/weston/blob/master/protocol/weston-touch-calibration.xml


Thanks,
pq
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