This is Milestone 1 of full support of Atomic Mode Setting (AMS) and
Universal Planes in the KWin DRM backend.
With Milestone 1 we can use the primary plane of a DRM output and do an
AMS commit (this means mode setting aswell as page flipping), if the
driver supports it. Until now the functionality is only tested on Intel
graphics. You need the drm-next kernel for most recent DRM kernel
developments. As boot option set "i915.nuclear_pageflip". Additionally
at the moment AMS is still hidden behind the environment variable
KWIN_DRM_AMS. Set it, if you want to try out AMS.
What needs to be done next: Make it possible to transfer EGL buffers
directly to planes and implement logic for deciding about using a plane
or not for a specific buffer.
You can read more about it on LWN:
https://lwn.net/Articles/653071
And on Martin's blog:
https://blog.martin-graesslin.com/blog/2015/08/layered-compositing/
I used as model previous work by Daniel Stone for Weston:
https://git.collabora.com/cgit/user/daniels/weston.git
Reviewed-by: mgraesslin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D2370
Summary:
If it's not possible to create a buffer to blank the output, KWin won't
be able to render to the output. In that case the output should not be
added to the list of outputs.
To support this DrmOutput::blank and DrmOutput::init return bool to
indicate whether they succeeded. DrmBackend handles this situation and
doesn't add the output to the list of outputs if init failed.
If after init there are no outputs KWin is in a state where it won't
be functional. Thus the platform emits the initFailed signal to
terminate.
BUG: 365242
FIXED-IN: 5.7.2
Test Plan: No hardware to reproduce the condition
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D2135
Summary:
Source code reorganization:
The base class AbstractBackend got renamed to Platform, thus the
"backends" are "platforms" now. As they are plugins they should go
together with other KWin plugins which are nowadays in the folder
plugins.
So new location is plugins/platforms/
Reviewers: #plasma, sebas
Subscribers: plasma-devel
Projects: #plasma
Differential Revision: https://phabricator.kde.org/D1353
