The output backend API is now mostly state-less thanks to the atomic
hooks (commit and test). There is one exception though: attach_render.
This function makes the rendering context current. However sometimes the
compositor might decide not to render after attach_render (e.g. when
there's nothing new to render to the back buffer). Thus
wlr_output_rollback has been introduced to revert the pending state.
Because the output backend API is mostly state-less, the only thing
wlr_output_impl.rollback needs to do is revert the current rendering
context. Rename the function to rollback_render to make this clear. Add
a check in the common wlr_output code to only call rollback_render when
attach_buffer has been previously called.
On the long term, we'll be able to remove attach_render and
rollback_render together.
GCC is complaining about a maybe-uninitialized variable when doing a
release build. Even if that can't actually happen because all enum
values are handled, add an abort call to silence the warning.
Most of the pending output state is not forwarded to the backend prior
to an output commit. For instance, wlr_output_set_mode just stashes the
mode without calling any wlr_output_impl function.
wlr_output_impl.commit is responsible for applying the pending mode.
However, there are exceptions to this rule. The first one is
wlr_output_attach_render. It won't go away before renderer v6 is
complete, because it needs to set the current EGL surface.
The second one is wlr_output_attach_buffer.
wlr_output_impl.attach_buffer is removed in [1].
When wlr_output_rollback is called, all pending state is supposed to be
cleared. This works for all the state except the two exceptions
mentionned above. To fix this, introduce wlr_output_impl.rollback.
Right now, the backend resets the current EGL surface. This prevents GL
commands from affecting the output after wlr_output_rollback.
This patch is required for FBO-based outputs to work properly. The
compositor might be using FBOs for its own purposes [2], having leftover
FBO state can have bad consequences.
[1]: https://github.com/swaywm/wlroots/pull/2097
[2]: https://github.com/swaywm/wlroots/pull/2063#issuecomment-597614312
Check that buffer can be scanned out in wlr_output_test instead of
wlr_output_attach_buffer. This allows the backend to have access to the
whole pending state when performing the check.
This brings the wlr_output API more in line with the KMS API.
This removes the need for wlr_output_attach_buffer to return a value,
and for wlr_output_impl.attach_buffer.
Consumers call wlr_buffer_lock. Once all consumers are done with the
buffer, only the producer should have a reference to the buffer. In this
case, we can release the buffer (and let the producer re-use it).
This patch disambiguates the needs_frame event by uncoupling it from
damage. A new separate damage event is emitted when the backend damages
the output (this happens e.g. VT is changed or software cursors are
used). The event specifies the damaged region.
The wlr_output.damage field is removed. wlr_output is no longer
responsible for tracking its own damage, this is wlr_output_damage's
job.
This is a breaking change, but wlr_output_damage users shouldn't need an
update.
Bugs fixed:
- Screen flashes on VT switch
- Cursor damage issues on the X11 and headless backends
Closes: https://github.com/swaywm/sway/issues/5086
This way, wlr_output_schedule_frame will always be followed by a
wlr_output_commit. This forces the compositor to render an extra
frame before stopping the rendering loop.
To test, run wleird's frame-callback [1], make sure it's the only
visible client on the output and check the interval between frame
events is the output's refresh period instead of zero.
[1]: https://github.com/emersion/wleird/blob/master/frame-callback.c
Closes: https://github.com/swaywm/wlroots/issues/2051
This function allowed backends to provide a custom function for frame
scheduling. Before resuming the rendering loop, the DRM and Wayland
backends would wait for vsync.
There isn't a clear benefit of doing this. The only upside is that we
get more stable timings: the delay between two repaints doesn't change too
much and is close to a mutliple of the refresh rate.
However this introduces latency, especially when a client misses a
frame. For instance a fullscreen game missing vblank will need to wait
more than a whole frame before being able to display new content. This
worst case scenario happens as follows:
- Client is still rendering its frame and cannot submit it in time
- Deadline is reached
- Compositor decides to stop the rendering loop since nothing changed on
screen
- Client finally manages to render its frame, submits it
- Compositor calls wlr_output_schedule_frame
- DRM backend waits for next vblank
- The wlr_output frame event is fired, compositor draws new content on screen
- On the second next vblank, the new content reaches the screen
With this patch, the wlr_output frame event is fired immediately when
the client submits its late frame.
This change also makes it easier to support variable refresh rate, since
VRR is all about being able to present too-late frames earlier.
References: https://github.com/swaywm/wlroots/issues/1925
This change ensures that wlr_output_transform_compose correctly composes
transforms when the first transform includes a rotation and the second
transform includes a flip.
wlr_output.description is a string containing a human-readable string
identifying the output. Compositors can customise it via
wlr_output_set_description, for instance to make the name more
user-friendly.
References: https://github.com/swaywm/wlroots/issues/1623
Backends not supporting presentation feedback call
wlr_output_send_present with a NULL event in their commit handler. Since
the commit hasn't been applied yet, commit_seq still has its old value.
We need to increment it.
An alternative would be to move commit_seq in wlr_output_state. This
would allow to have a pending and a current commit_seq.
wlr_output_send_present could take the pending commit_seq when called
with a NULL event.
This is set to the value of wlr_output.commit_seq when the frame has
been submitted. This allows tracking presentation with more then 1 full
frame of latency.
References: https://github.com/swaywm/wlroots/issues/1917
This commit makes more output properties (mode, enabled, scale and transform)
atomic. This means that they are double-buffered and only applied on commit.
Compositors now need to call wlr_output_commit after setting any of those
properties.
Internally, backends still apply properties sequentially. The behaviour should
be exactly the same as before. Future commits will update some backends to take
advantage of the atomic interface. Some backends are non-atomic by design, e.g.
the X11 backend or the legacy DRM backend.
Updates: https://github.com/swaywm/wlroots/issues/1640
The documentation for wayland-server.h says:
> Use of this header file is discouraged. Prefer including
> wayland-server-core.h instead, which does not include the server protocol
> header and as such only defines the library PI, excluding the deprecated API
> below.
Replacing wayland-server.h with wayland-server-core.h allows us to drop the
WL_HIDE_DEPRECATED declaration.
AFAIK this was always set to zero. Instead, compute wl_output mode flags on the
fly.
Technically this is a breaking change, but I don't think anybody uses this
field.
The backend doesn't need to handle transform changes, since everything is done
in software. In fact, all of the implementations were all identical and just
set the transform.
We could add support for hardware transforms, but:
- This would require a different field (something like hardware_transform)
- Not all combinations are possible because there often are hardware
limitations
- The Wayland protocol isn't ready for this (in particular xdg-output, see [1])
This belongs to a different patch series anyway.
[1]: https://patchwork.freedesktop.org/series/52324/
It can be surprising for callers to stash pending changes, commit, get a
failure, then set some other pending changes, commit again, and get another
failure because of the previously-pending changes.
Instead, make commit reset the pending state on failure.
If an output is destroyed while an idle_done event is scheduled, it
results in the following Address Sanitizer Output:
==1469==ERROR: AddressSanitizer: heap-use-after-free on address 0x6170000bb668 at pc 0x7f49aaa0c348 bp 0x7ffed5da35b0 sp 0x7ffed5da35a0
WRITE of size 8 at 0x6170000bb668 thread T0
#0 0x7f49aaa0c347 in schedule_done_handle_idle_timer ../subprojects/wlroots/types/wlr_output.c:265
#1 0x7f49aa2f875b in wl_event_loop_dispatch_idle (/usr/lib/libwayland-server.so.0+0xa75b)
#2 0x7f49aa2f8815 in wl_event_loop_dispatch (/usr/lib/libwayland-server.so.0+0xa815)
#3 0x7f49aa2f739b in wl_display_run (/usr/lib/libwayland-server.so.0+0x939b)
#4 0x556622dadd51 in server_run ../sway/server.c:216
#5 0x556622dac25d in main ../sway/main.c:397
#6 0x7f49aa0d0ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2)
#7 0x556622d8d09d in _start (/usr/local/bin/sway+0x3909d)
0x6170000bb668 is located 488 bytes inside of 672-byte region [0x6170000bb480,0x6170000bb720)
freed by thread T0 here:
#0 0x7f49aabc8f89 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:66
#1 0x7f49aa968fc2 in drm_connector_destroy ../subprojects/wlroots/backend/drm/drm.c:829
#2 0x7f49aaa0cc52 in wlr_output_destroy ../subprojects/wlroots/types/wlr_output.c:357
#3 0x7f49aa96d2e9 in scan_drm_connectors ../subprojects/wlroots/backend/drm/drm.c:1265
#4 0x7f49aa961a59 in drm_invalidated ../subprojects/wlroots/backend/drm/backend.c:135
#5 0x7f49aaa2e1e9 in wlr_signal_emit_safe ../subprojects/wlroots/util/signal.c:29
#6 0x7f49aa98319f in udev_event ../subprojects/wlroots/backend/session/session.c:52
#7 0x7f49aa2f87f1 in wl_event_loop_dispatch (/usr/lib/libwayland-server.so.0+0xa7f1)
previously allocated by thread T0 here:
#0 0x7f49aabc95a1 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:95
#1 0x7f49aa96b7a2 in scan_drm_connectors ../subprojects/wlroots/backend/drm/drm.c:1114
#2 0x7f49aa961a59 in drm_invalidated ../subprojects/wlroots/backend/drm/backend.c:135
#3 0x7f49aaa2e1e9 in wlr_signal_emit_safe ../subprojects/wlroots/util/signal.c:29
#4 0x7f49aa98319f in udev_event ../subprojects/wlroots/backend/session/session.c:52
#5 0x7f49aa2f87f1 in wl_event_loop_dispatch (/usr/lib/libwayland-server.so.0+0xa7f1)
SUMMARY: AddressSanitizer: heap-use-after-free ../subprojects/wlroots/types/wlr_output.c:265 in schedule_done_handle_idle_timer
Shadow bytes around the buggy address:
0x0c2e8000f670: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c2e8000f680: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c2e8000f690: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c2e8000f6a0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c2e8000f6b0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x0c2e8000f6c0: fd fd fd fd fd fd fd fd fd fd fd fd fd[fd]fd fd
0x0c2e8000f6d0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c2e8000f6e0: fd fd fd fd fa fa fa fa fa fa fa fa fa fa fa fa
0x0c2e8000f6f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c2e8000f700: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c2e8000f710: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Remove the idle_done idle timer when the output is destroyed
This commit introduces wlr_output_schedule_done and refactors the mechanism
used to send wl_output events to clients.
wlr_output_schedule_done schedules a wl_output.done event. This allows clients
to see wlr_output property changes as atomic.
This function is also useful for add-on interfaces like xdg_output which need
to trigger a wl_output.done event to apply their new state.
wlr_output_damage_make_current has been renamed to
wlr_output_damage_attach_render, since it's just a wrapper for
wlr_output_attach_render.
wlr_output_damage_swap_buffers has been removed completely. Instead,
wlr_output_damage now listens to successful wlr_output commits and updates its
internal state accordingly.
This updates the backend part of the output API. This is mostly renaming:
make_current becomes attach_render and swap_buffers becomes commit.
This also fixes the RDP backend to support NULL damage.
