gl_rendererer's output_pbuffer_create has a lot of arguments now. Add a
structure for the options to make it more clear what is what.
This is in preparation for adding bare-integer arguments which are ripe
for confusion when passing positional arguments.
Signed-off-by: Daniel Stone <daniels@collabora.com>
gl_rendererer's output_create has a lot of arguments now. Add a
structure for the options to make it more clear what is what.
This is in preparation for adding bare-integer arguments which are ripe
for confusion when passing positional arguments.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Just a couple of places which shouldn't be possible, so initialized and
added assertions to make sure.
Signed-off-by: Scott Anderson <scott.anderson@collabora.com>
If the gl-renderer is disabled build fails with:
../libweston/backend-headless/headless.c:394:9: error:
‘EGL_PLATFORM_SURFACELESS_MESA’ undeclared (first use in this function)
Fix this by including shared/weston-egl-ext.h.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Use the surfaceless platform in the headless backend to initialize the
GL-renderer and create pbuffer outputs. This allows headless backend to use
GL-renderer, even hardware accelerated.
This paves way for exercising GL-renderer in CI and using the Weston test suite
to test hardware GL ES implementations.
Relates to: https://gitlab.freedesktop.org/wayland/weston/issues/278
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Depending on system loading, weston-launcher could drop the drm
master access before the compositor and all the clients receive
the notification. In this case, some commit could be sent to the
drm driver too late and get refused with error EACCES.
This error condition is not properly managed and causes weston to
hang.
Change the return type of start_repaint_loop() and repaint_flush()
from void to int, and return 0 on success or -1 if the repaint has
to be cancelled.
In the callers of start_repaint_loop() and repaint_flush() handle
the return value and cancel the repaint when needed.
In backend-drm detect the error EACCES and return -1.
Note: to keep the code cleaner, this change inverts the execution
order between weston_output_schedule_repaint_reset() and
repaint_cancel().
No need to wait for suspend or for any notification; in case the
weston reschedules a repaint, it will get EACCES again.
At resume, damage-all guarantees a complete repaint.
This fix is for atomic modeset only.
Legacy modeset suffers from similar problems, but it is not fixed
by this change. Since drm_pending_state_apply() never returns
error for legacy modeset, this change has no impact on legacy
modeset.
Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
Fixes: https://gitlab.freedesktop.org/wayland/weston/issues/117
The backend headers are renamed from compositor-foo.h to backend-foo.h to
better describe their purpose. These headers are public libweston API for each
specific backend.
The headers will also be used like
#include <libweston/backend-drm.h>
instead of
#include <compositor-drm.h>
to give them a more explicit namespace.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
The main idea is to make libweston users use the form
#include <libweston/libweston.h>
instead of the plain
#include <compositor.h>
which is prone to name conflicts. This is reflected both in the installed
files, and the internal header search paths so that Weston would use the exact
same form as an external project using libweston would.
The public headers are moved under a new top-level directory include/ to make
them clearly stand out as special (public API).
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Introduce support for the zwp_linux_explicit_synchronization_unstable_v1
protocol with an implementation of the zwp_linux_explicit_synchronization_v1
interface.
Explicit synchronization provides a more versatile notification
mechanism for buffer readiness and availability, and can be used to
improve efficiency by integrating with related functionality in display
and graphics APIs.
In addition, the per-commit nature of the release events provided by
this protocol potentially offers a solution to a deficiency of the
wl_buffer.release event (see
https://gitlab.freedesktop.org/wayland/wayland/issues/46).
Support for this protocol depends on the capabilities of the backend, so
we don't register it by default but provide a function which each
backend will need to call. In this commit only the headless backend when
using the noop renderer supports this to enable testing.
Note that the zwp_surface_synchronization_v1 interface, which contains
the core functionality of the protocol, is not implemented in this
commit. Support for it will be added in future commits.
Changes in v7:
- Added some information in the commit message about the benefits of
the explicit sync protocol.
Changes in v6:
- Fall back to advertising minor version 1 of the explicit sync protocol,
although we support minor version 2 features, until the new
wayland-protocols version is released.
Changes in v5:
- Meson support.
- Advertise minor version 2 of the explicit sync protocol.
Changes in v4:
- Enable explicit sync support in the headless backend for all
renderers.
Changes in v3:
- Use wl_resource_get_version() instead of hardcoding version 1.
- Use updated protocol interface names.
- Use correct format specifier for resource id.
- Change test name to 'linux-explicit-synchronization.weston'
(s/_/-/g).
Changes in v2:
- Move implementation to separate file so protocol can be registered
on demand by backends.
- Register protocol in headless+noop backend for testing purposes.
Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
Add a flag to pixman-renderer for initializing the output with a shadow
framebuffer. All backends were getting the shadow implcitly, so all
backends are modified to ask for the shadow explicitly.
Using a shadow buffer is usually beneficial, because read-modify-write
cycles (blending) into a scanout-capable buffer may be very slow. The
scanout framebuffer may also have reduced color depth, making blending
and read-back produce inferior results.
In some use cases though the shadow buffer might be just an extra copy
hurting more than it helps. Whether it helps or hurts depends on the
platform and the workload. Therefore let the backends control whether
pixman-renderer uses a shadow buffer for an output or not.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Implement the head-based output API in this backend, and stop relying on
the implicit weston_output::head.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Derek Foreman <derekf@osg.samsung.com>
In order to support clone modes, libweston needs the concept of a head
that is separate from weston_output. While weston_output manages buffers
and the repaint state machine, weston_head will represent a single
monitor. In the future it will be possible to have a single
weston_output drive one or more weston_heads for a clone mode that
shares the framebuffers between all cloned heads.
All the fields that are obviously properties of the monitor are moved
from weston_output into weston_head.
As moving the fields requires one to touch all the backends for all the
assingments, introduce setter functions for them while we are here. The
setters are identical to the old assignments, for now.
As a temporary measure, weston_output embeds a single head. Also the
ugly casts in weston_head_set_monitor_strings() will be removed by a
follow-up patch.
Libweston major version is bumped, because weston_output struct layout
is changed.
v7:
- Bump libweston major version.
v6:
- adapt to upstream changes in weston_output_set_transform()
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v5 Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
v6 Reviewed-by: Ian Ray <ian.ray@ge.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Derek Foreman <derekf@osg.samsung.com>
This was used from the crash handlers, which do not exist anymore.
Nothing calls restore, so delete the dead code.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Change all backends to set the core backend pointer early.
This is necessary for libweston core to be able to access the backend
vfuncs before the backend init function returns. Particularly,
weston_output_init() will be needing to inspect the backend vfuncs to
see if the backend has been converted to a new API. Backends that create
outputs as part of their init would fail without setting the pointer
earlier.
For consistency, all backends are modified instead of just those that
could hit an issue.
Libweston core will take care of resetting the backend pointer to NULL
in case of error since "libweston: ensure backend is not loaded twice".
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Acked-by Daniel Stone <daniels@collabora.com>
'release' is a more appropriate name because the function does not free
the underlying memory. The main reason for this is that we need the name
weston_output_destroy() for new API that actually will free also the
underlying memory.
Since the function is only used in backends and external backends are
not a thing, this does not cause libweston major version bump, even
though it does change the ABI. There is no way external users could have
successfully used this function.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Acked-by Daniel Stone <daniels@collabora.com>
Add 'name' argument to weston_output_init(). This is much more obvious
than the assert inside weston_output_init() to ensure the caller has set
a field in weston_output first.
Now weston_output_init() will strdup() the name itself, which means we
can drop a whole bunch of strdup()s in the backends. This matches
weston_output_destroy() which was already calling free() on the name.
All backends are slightly reordered to call weston_output_init() before
accessing any fields of weston_output, except the Wayland backend which
would make it a little awkward to do it in this patch. Mind, that
weston_output_init() still does not reset the struct to zero - it is
presumed the caller has done it, since weston_output is embedded in the
backend output structs.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Reviewed-by: David Fort <contact@hardening-consulting.com>
[Daniel: document name copying]
Acked-by Daniel Stone <daniels@collabora.com>
Initialize the list in weston_output_init() instead of doing it
separately in each backend.
One would expect weston_output_init() to initialize all weston_output
members, at least those that are not NULL.
We rely on the set_size() functions to be called only once, as is
assert()'d. If set_size() becomes callable multiple times, this patch
will force them to be fixed to properly manage the mode list instead of
losing all members.
compositor-wayland.c is strange in
wayland_output_create_for_parent_output(): it first called
wayland_output_set_size() that initialized the mode list with a single
mode manufactured from width and height and set that mode as current.
Then it continued to reset the mode list and adding the list of modes
from the parent output, leaving the current mode left to point to a mode
struct that is no longer in the mode list and with a broken 'link'
element. This patch changes things such that the manufactured mode is
left in the list, and the parent mode list is added. This is probably
not quite right either.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Emre Ucan <eucan@de.adit-jv.com>
Reviewed-by: Ian Ray <ian.ray@ge.com>
Acked-by Daniel Stone <daniels@collabora.com>
Implement new repaint_begin and repaint_flush hooks inside
weston_backend, allowing backends to gang together repaints which
trigger at the same time.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
This prevents loading a backend as a simple module. This will avoid
messing up with backends when we will introduce libweston common
modules.
Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Daniel Stone <daniels@collabora.com>
This is a complete port of the headless backend that
uses the recently added output handling API for output
configuration.
- Output can be configured at runtime by passing the
necessary configuration parameters, which can be
filled in manually, obtained from the configuration
file or obtained from the command line using
previously added functionality. It is required that
the scale and transform values are set using the
previously added functionality.
- Output can be created at runtime using the output
API. The output creation only creates a pending
output, which needs to be configured the same way as
mentioned above.
After everything has been set, output needs to be
enabled manually using weston_output_enable().
Same as before, a single output is created at runtime
using the default configuration or a configuration
parsed from the command line. The no-outputs
functionality is also preserved, which means that no
output will be created initially, but more outputs can
be added at runtime using the output API.
New feature:
This patch also adds, as a bonus of using shared
functionality, support for setting options for outputs
created by this backend in the weston config file in
addition to setting them from the command line.
v2:
- Fix wet_configure_windowed_output_from_config() usage.
- Call headless_output_disable() explicitly from
headless_output_destroy().
v3:
- Add scale support to output width and height.
- Use scaled values in calls to various functions which
require width and height.
- Disallow calling headless_output_configure more than once.
- Remove unneeded checks for output->name == NULL as that
has been disallowed.
- Use weston_compositor_add_pending_output().
- Bump weston_headless_backend_config version to 2.
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Armin Krezović <krezovic.armin@gmail.com>
This uses container_of instead of explicit cast to retrieve
backend and output objects from generic weston_backend and
weston_output pointers.
Signed-off-by: Armin Krezović <krezovic.armin@gmail.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
This patch adds a new command line option which can be
used to tell headless backend not to create any
virtual outputs.
This will be used for output hotplug emulation, where
weston will start with no outputs available, and the
virtual output will be created at runtime.
v2:
- Use bool instead of int for the indicator flag
- Move final newspace to a separate line in command
line options
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Armin Krezović <krezovic.armin@gmail.com>
This clarifies what is supposed to be the libweston code.
v2: screen-share.c is already in compositor/ instead.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Yong Bakos <ybakos@humanoriented.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Tested-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Tested-by: Benoit Gschwind <gschwind@gnu-log.net>
Acked-by: Benoit Gschwind <gschwind@gnu-log.net>
[Pekka: rebased]
The headless backend was creating a seat, but nothing would ever happen
on that seat, except the pointer cursor would show up.
Tests do not seem to use this seat either. weston-test.so plugin creates
its own seat to be controlled by the tests.
This is part of the series to get rid of cursors for screenshot-based
tests where they are not wanted.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
Backends do not have access to command line elements nor weston_config
anymore. They use the backend-specific config APIs now.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>
refactor configuration API of headless-backend
Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v6:
- Define version number in the header
- Don't use leading underscores in header guards
- Add stub config_init_to_defaults()
- Allocate config on stack
- Drop unused display_name parameter
- Add error message when config is invalid
- Install compositor-headless.h and list it in headless-backend sources
v5:
- Update to current trunk
- Fixed typo 'struct weston_wayland_backend_config'
- Dropped unused variables
- Dropped weston_headless_backend_config_create() in favor of
directly zalloc'ing the object
- Dropped weston_headless_backend_load() in favor of the more
generalized load_backend_new().
- Dropped typedef from header
- Restored use of 'backend_init' entry point
- Backend_init() takes a base weston_backend_config object
- Renamed 'param' to 'config' in a few places for consistency
- Renamed 'headless_options' variable to 'options for consistency
- Version the base struct
- Free config on error
- Don't free config during backend_init normal operations
- Adjust header ordering
- Make header guard naming consistent with other headers
- Light reformatting for code style and consistency with other
backend config patches
Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>
[Pekka: rebased to apply before drm and x11 backends]
[Pekka: squashed in the headless part of "Enforce destruction of all
backend config objects after initialization"]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Remove the unstable presentation_timing.xml file, and use
presentation-time.xml from wayland-protocols instead to generate all the
Presentation extension bindings.
The following renames are done according to the XML changes:
- generated header includes
- enum constants and macros prefixed with WP_
- interface symbol names prefixed with wp_
- protocol API calls prefixed with wp_
Clients use wp_presentation_interface.name rather than hardcoding the
global interface name: presentation-shm, weston-info, presentation-test.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
[Pekka: updated wayland-protocols dependency to 1.2]
Add new configuration argument to the backend_init() function, which
will replace the current argc, argv, and config arguments.
After each backend is converted individually the unused parameters
will be removed.
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
This commit adds three new exported functions:
- weston_compositor_create() returns a new weston_compositor instance,
initializing it as the now removed weston_compositor_init() did.
- weston_compositor_exit(compositor) asks the compositor to tear
down by calling the compositor's exit vfunc which is set by the
libweston application.
- weston_compositor_destroy(compositor) is called by the libweston
application when tearing down the compositor. The compositor is destroyed
and the memory freed.
Reviewed-by: Jon A. Cruz <jonc@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
This is a preliminary change for libweston, with no functional modifications.
Separate the backends and the core weston_compositor struct, by creating
the weston_compositor in the main(), and having the various backends extend
the weston_backend struct, an instance of which is returned by the backend
entry point.
This enable us to logically separate the compositor core from the backend,
allowing the core to be extended without messing with the backends.
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
To help reduce code duplication and also 'kitchen-sink' includes
the ARRAY_LENGTH macro was moved to a stand-alone file and
referenced from the sources consuming it. Other macros will be
added in subsequent passes.
Signed-off-by: Jon A. Cruz <jonc@osg.samsung.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
The compositor's output_created signal used to be sent in weston_output_init()
which the backend call before putting the output in the output_list.
This caused problems when creating a new view in a listener to that signal,
because weston_view_assign_output() doesn't yet know the new output exists.
To fix this add a new weston_composito_add_output() func which adds the
output in the list and later sends the signal, and make the backends call
that.
Create a new function weston_compositor_read_presentation_clock() to
wrap the clock_gettime() call for the Presentation clock.
Reading the presentation clock is never supposed to fail, but if it
does, this will notify about it. I have not seen it fail yet, though.
This prepares for new testing features in the future that might allow
controlling the presentation clock. Right now it is just a convenience
function for clock_gettime().
All presentation clock readers are converted to call this new function
except rpi-backend's rpi_flippipe_update_complete(), because it gets its
clock id via a thread-safe mechanism. There shouldn't be anything really
thread-unsafe in weston_compositor_read_presentation_clock() at the
moment, but might be in the future, and weston core is not expected to
need to be thread-safe.
This is based on the original patch by
Cc: Derek Foreman <derekf@osg.samsung.com>
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-By: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
60 millihertz is a bit low, let's make it 60 Hz as it was supposed to
be.
When the new repaint scheduling algorithm gets implemented, this
fixes 'make check' taking almost 3 minutes instead of the normal 3
seconds, when running with 7 millisecond repaint window.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Change weston_output_finish_frame() signature so that backends are
required to set the flags, that will be reported on the Presentation
'presented' event. This is meant for output-wide feedback flags. Flags
that vary per wl_surface are subject for the following patch.
All start_repaint_loop functions use the special private flag
PRESENTATION_FEEDBACK_INVALID to mark, that this call of
weston_output_finish_frame() cannot trigger the 'presented' event. If it
does, we now hit an assert, and should then investigate why a fake update
triggered Presentation feedback.
DRM:
Page flip is always vsync'd, and always gets the completion timestamp
from the kernel which should correspond well to hardware. Completion is
triggered by the kernel/hardware.
Vblank handler is only used with the broken planes path, therefore do
not report VSYNC, because we cannot guarantee all the planes updated at
the same time. We cannot set the INVALID, because it would abort the
compositor if the broken planes path was ever used. This is a hack that
will get fixed with nuclear pageflip support in the future.
fbdev:
No vsync, update done by copy, no completion event from hardware, and
completion time is totally fake.
headless:
No real output to update.
RDP:
Guessing that maybe no vsync, fake time, and copy make sense (pixels
sent over network). Also no event that the pixels have been shown?
RPI:
Presumably Dispmanx updates are vsync'd. We get a completion event from
the driver, but need to read the clock ourselves, so the completion time
is somewhat unreliable. Zero-copy flag not implemented though it would
be theoretically possible with EGL clients (zero-copy is a per-surface
flag anyway, so in this patch).
Wayland:
No information how the host compositor is doing updates, so make a safe
guess without assuming vsync or hardware completion event. While we do
get some timestamp from the host compositor, it is not the completion
time. Would need to hook to the Presentation extension of the host
compositor to get more accurate flags.
X11:
No idea about vsync, completion event, or copying. Also the timestamp is
a fake.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Acked-by: Mario Kleiner <mario.kleiner.de@gmail.com>
We now allow --transform with the headless compositor, however it still
doesn't parse anything out of weston.ini
Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Allow the headless backend to render into an off screen buffer with pixman.
Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Add presentation clock setters that verify the given clock actually
works. Offer an automatic choice of a software fallback clock, when a
backend has to always use clock_gettime() to approximate the
presentation time.
The DRM backend already queried the DRM about the clock id, just let the
DRM backend set the presentation clock from that.
For all other backends which do not get a timestamp from the driver,
call the software clock setter to choose a suitable clock.
Report the chosen clock via presentation.clock_id event to clients.
In finish_frame(), upgrade the argument from uint32_t milliseconds to
struct timespec which can accurately hold the presentation clock values.
This will be needed when weston_output_finish_frame() starts to send out
presentation_feedback.presented events.
While at it, replace gettimeofday() calls with clock_gettime() using the
chosen presentation clock, so we manufacture presentation timestamps
from the presentation clock when the gfx drivers cannot give us a proper
timestamp.
Rpi patch is more verbose due to not having the compositor pointer
available in rpi_flippipe_update_complete(). Explicitly carry the clock
id with flippipe so it is available in the thread.
Changes in v4:
* rpi debug build fix
v4 Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Fixes a segfault when using compositor-headless for the test suite
as many tests assume there are input devices and try to use them
through the wl_test interface.
Signed-off-by: Emilio Pozuelo Monfort <emilio.pozuelo@collabora.co.uk>
Currently we destroy the renderer before the outputs are destroyed, but
that sometimes leads to an error since a reference to the renderer is
necessary in order to destroy a gl_renderer_output.
Since destroying the renderer is common among all backends, just move
that call into weston_compositor_shutdown() immediately after the
outputs being destroyed.
If we are about to finish a frame, but a redraw is pending and we let the
compositor redraw, we need to check for errors. If the redraw fails and
the backend cannot schedule a page-flip, we need to finish the frame,
anyway.
All backends except DRM use a timer to schedule frames. Hence, they cannot
fail. But for DRM, we need to be able to handle drmModePageFlip() failures
in case access got revoked.
This fixes a bug where logind+drm caused keyboard input to be missed as we
didn't reenable it after a failed page-flip during deactivation.