HDR support in Wayland/Weston

Michel Dänzer michel at daenzer.net
Thu Mar 7 10:15:16 UTC 2019

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

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