HDR support in Wayland/Weston

[Chris Murphy]

On Thu, Mar 7, 2019 at 3:15 AM Michel Dänzer <michel at daenzer.net> wrote:
>
> On 2019-03-07 8:05 a.m., Chris Murphy wrote:

> > Of course. It can take 5-30 minutes to do a calibration and
> > characterization. In particular if I have 2, 3 or even 4 displays
> > connected I'd want to calibrate them in sequence while the others are
> > being used for useful tasks.
>
> It sounds like KMS leases could be a pretty good fit for a calibration
> application. It can lease each output individually from the Wayland
> compositor and fully control it using KMS APIs, while the Wayland
> compositor continues running normally on other outputs.

If developers of such applications need to do substantially different
things on each platform, it's a big negative. The only point for using
drm/kms is if it's easier for the developer, whether they use it
directly or through some kind of abstraction that can be expected to
work in the same code base and easily do the right thing whether the
application depends on Xorg or an arbitrary Wayland compositor.
Otherwise, it's effectively a proliferation of platforms.

I don't have numbers, but my handwavy guess is full screen versus
floating window display calibration applications is about 50/50. So
it's a substantial UI/UX change to ask some developers to expect to
have to rebuild for full screen only, rather than some kind of cut out
in a window.

Also, calibration/profiling tools do verification and are often used
for troubleshooting and diagnosis. So they are extra special in that
they need a calibration mode, as well as a normal mode to verify both
calibration and characterization. And if switching between them is
akin to parking the car, getting out, getting into a semi-truck,
driving 100 meters, parking the truck, getting out, walking back to
and getting into the car to resume - that's not just a PITA for them,
it makes them less simple. And the simpler they can be, the easier
they are to maintain, and more trustworthy they are as both diagnostic
and calibration/characterization tools.


-- 
Chris Murphy