The drm fd can get stuck in readable state, in which case the
QSocketNotifier will fire the activated signal as often as it can
leading to high cpu usage.
We need to read() the drm fd in order to make the socket notifier stop
firing QSocketNotifier::activated.
This change removes the m_platform->isActive() check to ensure that
drmHandleEvent() gets called, in general, it should be safe as we only
notify the outputs about completed pageflips.
BUG: 452726
Currently the Workspace processes output updates as they occur, e.g.
when the drm backend scans connectors, the Workspace will handle
hotplugged outputs one by one or if an output configuration changes the
mode of several outputs, the workspace will process output layout
updates one by one instead of handling it in one pass. The main reason
for the current behavior is simplicity.
However, that can create issues because it's possible that the output
layout will be temporarily in degenerate state and features such as
sticking windows to their outputs will be broken.
In order to fix that, this change makes the Workspace process batched
output updates. There are several challenges - disconnected outputs have
to be alive when the outputsQueried signal is emitted, the workspace
needs to determine what outputs have been added or removed on its own.
The proposed way to handle unplugged gpus allows us to ensure that
removed outputs' lifetime can be extended to the moment when the
Platform::outputsQueried signal is emitted.
Besides that, it's possible to extend this code a bit further to make
sure that output updates are batched when hotplugging multiple gpus,
e.g. after resuming, etc.
Currently, we effectively almost everywhere need DrmOutput outputs,
DrmVirtualOutput outputs are needed only in a couple of places. There's
not a lot that we gain from storing real and virtual outputs in one
list, it adds unnecessary casting, etc. Ideally, virtual outputs must
come from a different backend, the current approach is not scalable.
This std::sort() function traces its origin back to
cbbd684430. The sort step was necessary to
ensure that we get same configuration hash regardless the order in which
outputs were connected.
On the other hand, our KWinKScreenIntegration code already does that so
it seems excessive to sort outputs the second time.
Placeholder outputs are not rendered so they don't need render data.
Also, this simplifies the control flow when the last real output is
removed. The Platform::screensQueried signal won't be emitted inside a
Platform::screensQueried slot.
Things such as Output, InputDevice and so on are made to be
multi-purpose. In order to make this separation more clear, this change
moves that code in the core directory. Some things still link to the
abstraction level above (kwin), they can be tackled in future refactors.
Ideally code in core/ should depend either on other code in core/ or
system libs.
If multiple properties that affect the geometry change, then the
Output::geometryChanged() signal will be emitted multiple times, which
in its turn may force the Workspace to re-arrange windows, etc.
With this, the geometryChanged signal will be emitted in more expected
fashion only once as long as relevant property changes are batched.
Backends aren't the right layer to take care of placeholder outputs, and
don't really have enough information to do it either. This also fixes a
crash, because the placeholder output currently gets created too late
The main motivation behind moving kscreen integration to the
Workspace is to make output configuration work the same way
regardless of the backend and simplify the drm backend.
If the platform does not support configuring outputs, applying a config
must fail. However, almost all output backends support output
configuring except, perhaps, the x11 backend, but that case doesn't
matter.
It implicitly already is not copyable, due to the unique_ptr member.
However, Qt6 moc code isn't realizing that and fails to compile the
DrmPlane Q_GADGET sub-class of this.
Buffers with implicit modifiers from another GPU must not be imported, as
the layouts may not be compatible.
For buffers with incompatible modifiers, direct scanout can also be rejected
early, saving some computational power.
BUG: 457851
Two things about the code were wrong:
1. m_current is used in updateBlob() but was only updated afterwards
2. the assumption that the property having the same ID means it has the
same blob contents is not always true
BUG: 449285
This breaks cyclic dependency between Compositor and DRM backend, there
are still indirect dependencies though. However, fewer cyclic
dependencies should make the architecture more cleaner and easier to
tweak.
At the moment, a platform should provide two output lists - one that
lists all available outputs, and the other one that contains only
enabled outputs. In general, this amounts to some boilerplate code and
forces backends to be implemented in some certain way, which sometimes
is inconvenient, e.g. if an output is disabled or enabled, it will be
simpler if we only change Output::isEnabled(), otherwise we need to
start accounting for corner cases such as the order in which
Output::isEnabled() and Platform::enabledOutputs() are changed, etc.
This can be used to make our backends more multi-purpose. At the moment,
new outputs are enabled by default, but it makes sense to do otherwise.
For example, if an output is disabled by default, it would be possible
to delegate initial output configuration to layer above, to kwin.
In long term, the drm backend would need to scan connectors, create an
Output for every one of them, kwin sees new outputs and tries to apply
the initial output configuration, which includes the enabled status.
OutputMode provides a more robust way to refer to outputs. A mode can
have flags and things as such that are not taken into account with mode
+ refresh rate.
Instead of checking for properties needing a modeset, do atomic tests
with ALLOW_MODESET where it makes sense, and do a second atomic test
afterwards without ALLOW_MODESET to check if the modeset can be skipped.
This should ensure that KWin always does a modeset when it needs to do one,
and not do a modeset when it's not necessary. Doing this also allows
reducing the complexity of the drm backend a bit.
The DrmOutput synchronizes the enabled state with the active state,
which makes sense on one hand, but on the other hand, that's not good.
The drm backend makes a decision that should be ideally made by either
kscreen (turn on outputs before applying an output config), user, or
kwin itself.
This would also allow kwin to control the allocation of crtcs for
non-desktop outputs, which is a minor thing, but it might be useful in
the future.
infiniteRegion() is useful not only to effects but also other kwin
components, so move it to kwinglobals.h in order to make backends stop
depending on libkwineffects
This fixes the drm backend adding hotplugged gpus that belong to other
seats and makes the udev helper depend on less stuff from the layer
above backends.
The Session can be useful not only to the platform backend but also
input backends and for things such as vt switching, etc. Therefore it's
better to have the Application own the Session.
This is a too niche feature. It also doesn't have to be implemented in
the compositor. The kernel provides a way to overwrite the edid blob,
which is not specific to the running compositor.
