HDR support in Wayland/Weston

[Michel Dänzer]

On 2019-03-07 8:05 a.m., Chris Murphy wrote:
> On Wed, Mar 6, 2019 at 10:02 PM Graeme Gill <graeme2 at argyllcms.com> wrote:
>>
>> Chris Murphy wrote:
>>
>>> Hmmm. For a while now we've had display calibration+profiling
>>> applications compel full screen mode so they're not really usable
>>> alongside anything else. They are in effect taking over. So if it's
>>> possible for the calibration app to set aside the Wayland session, use
>>> drm/kms full screen, and then restore the Wayland session I might be
>>> OK with it. But if I have to log out, not OK.
>>
>> Sorry, as a Color Management application writer, I'm
>> not OK with it. I'd be better off firing up my own complete
>> copy of Wayland with the CM API's in it and use it
>> to talk to drm/kms, rather than trying to write an app to
>> talk direct to drm/kms. And of course if that's the easiest
>> course, why do that - just incorporate the CM API's in
>> stock Wayland and be done with it!
> 
> Not every desktop environment is using the same Wayland compositor, or
> even a Wayland compositor at all. So is drm/kms something you can
> depend on most of the time regardless of the desktop?
> 
> [...]
> 
> 
>> [ And why should Linux/Wayland be crippled compared to
>>   every other system ? I can and do do things like fire up
>>   a test patch display using ArgyllCMS/dispwin in one corner of my
>>   screen while running ArgyllCMS/spotread in another window to
>>   measure the patches. There's no reason not to, and every reason
>>   to be able to. ]
> 
> 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.


-- 
Earthling Michel Dänzer               |              https://www.amd.com
Libre software enthusiast             |             Mesa and X developer