In output_ensure_buffer() we create a swapchain and attach an empty
buffer to the output if necessary. We do that during the first commit.
This is fine when the first commit enables the output, however this breaks
when the first commit disables the output. A commit which disables an
output and has a buffer attached is invalid (see output_basic_test()), and
makes the DRM backend crash:
00:00:00.780 [wlr] [backend/drm/drm.c:622] connector eDP-1: Turning off
../subprojects/wlroots/backend/drm/drm.c:652:44: runtime error: member access within null pointer of type 'struct wlr_drm_crtc'
AddressSanitizer:DEADLYSIGNAL
=================================================================
==2524==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f22e894afc1 bp 0x7ffe1d57c550 sp 0x7ffe1d57c420 T0)
==2524==The signal is caused by a READ memory access.
==2524==Hint: address points to the zero page.
#0 0x7f22e894afc1 in drm_connector_commit_state ../subprojects/wlroots/backend/drm/drm.c:652
#1 0x7f22e894b1f5 in drm_connector_commit ../subprojects/wlroots/backend/drm/drm.c:674
#2 0x7f22e89e8da9 in wlr_output_commit_state ../subprojects/wlroots/types/output/output.c:756
#3 0x555ab325624d in apply_output_config ../sway/config/output.c:517
#4 0x555ab31a1aa1 in handle_new_output ../sway/desktop/output.c:974
#5 0x7f22e9272f6d in wl_signal_emit_mutable (/usr/lib/libwayland-server.so.0+0x9f6d)
#6 0x7f22e899b012 in new_output_reemit ../subprojects/wlroots/backend/multi/backend.c:161
#7 0x7f22e9272f6d in wl_signal_emit_mutable (/usr/lib/libwayland-server.so.0+0x9f6d)
#8 0x7f22e895a153 in scan_drm_connectors ../subprojects/wlroots/backend/drm/drm.c:1488
#9 0x7f22e893c2e4 in backend_start ../subprojects/wlroots/backend/drm/backend.c:24
#10 0x7f22e892ed00 in wlr_backend_start ../subprojects/wlroots/backend/backend.c:56
#11 0x7f22e8999b83 in multi_backend_start ../subprojects/wlroots/backend/multi/backend.c:31
#12 0x7f22e892ed00 in wlr_backend_start ../subprojects/wlroots/backend/backend.c:56
#13 0x555ab317d5cc in server_start ../sway/server.c:316
#14 0x555ab317748d in main ../sway/main.c:400
#15 0x7f22e783c28f (/usr/lib/libc.so.6+0x2328f)
#16 0x7f22e783c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
#17 0x555ab3134c84 in _start (/home/simon/src/sway/build/sway/sway+0x377c84)
Fixes: 3be6658ee7 ("output: allocate swapchain on first commit")
Closes: https://github.com/swaywm/sway/issues/7373
On first commit, require a new buffer if the compositor called a
mode-setting function, even if the mode won't change. This makes it
so the swapchain is created now.
Stop trying to check whether the backend supports buffer-less modesets
because that makes everything more complicated. For instance, the
DRM backend doesn't need a new buffer if the previous DRM master left
the output enabled.
Closes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3499
Closes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3502
Some compositors want to have full control over the buffers attached
to the output, and don't want to use the internal swapchain. Such
compositors include KWinFT (allocates its buffers on its own) and
gamescope (uses a headless output without any buffers).
Let's just make output_ensure_buffer() a no-op in that case.
In wlr_output_attach_render(), stop setting
wlr_output.pending.buffer. This removes one footgun: using the
wlr_buffer at that stage is invalid, because rendering operations
haven't been flushed to the GPU yet. We need to wait until
output_clear_back_buffer() for the wlr_buffer to be used safely.
Instead, set wlr_output.pending.buffer in wlr_output_test() and
wlr_output_commit().
Additionally, move the output_clear_back_buffer() from
wlr_output_commit_state() to wlr_output_commit(). This reduces the
number of calls in the failure path.
If the first test in output_ensure_buffer() fails with modifiers we
replace the swapchain with a modifierless swapchain and try again.
However if that fails as well the output is currently stuck without
modifiers until the next modeset.
To fix this, destroy the modifierless swapchain if the test using it
fails. The next output_attach_back_buffer() call will create a swapchain
that allows modifiers when needed.
This refactors output_ensure_buffer() to not mutate the state passed,
making the previous subtle behavior much more explicit.
Fixes: d483dd2f ("output: add wlr_output_commit_state")
Closes: #3442
DRM formats with an empty modifier list are invalid. Instead of
emptying the list, reduce it to { INVALID }.
Add a check to make sure the renderer and backend support implicit
modifiers, so that we don't fallback on e.g. Vulkan.
Closes: https://github.com/swaywm/sway/issues/6692
This allows compositors to get primary formats without manually
calling wlr_output_impl.get_primary_formats.
For example, the Sway patch for linux-dmabuf feedback [1] needs
this.
[1]: https://github.com/swaywm/sway/pull/6313
This change introduces new double buffered state to the wlr_output,
corresponding to the buffer format to render to.
The format being rendered to does not control the bit depth of colors
being sent to the display; it does generally determine the format with
which screenshot data is provided. The DRM backend _may_ sent higher
bit depths if the render format depth is increased, but hardware and
other limitations may apply.
Most (and possibly all) compositors using wlroots only ever render
fully opaque content. To provide better performance, this change
switches the default format used by wlr_output buffers from
ARGB8888 to the opaque XRGB8888.
Compositors like mutter, kwin, and weston already default to
XRGB8888, so this change is unlikely to expose any new bugs in
underlying drivers and hardware.
This does not affect the hardware cursor's buffer format, which is
still ARGB8888 by default.
As part of this change, the X11 backend (which does not support
changing format at runtime) now picks a true color, 24 bit depth
visual (i.e. XRGB8888) instead of a 32 bit depth (ARGB8888) one.
This makes it possible for the two functions using output_pick_format
(output_pick_cursor_format and output_create_swapchain) to select
different buffer formats.
The backend and renderer don't directly interact together, so there's
no point in checking that their buffer caps intersect. What we want to
check is that:
- The backend and allocator buffer caps are compatible, because the
backend consumes buffers to display them.
- The renderer and allocator buffer caps are compatible, because the
renderer imports buffers to sample them or render to them.
For instance, when running with the DRM backend and the Pixman renderer,
the (backend & renderer) check will fail because backend = DMABUF and
renderer = DATA_PTR.
This organizes the wlr_output implementation into separate files.
This avoids having a single mega-file with lots of unrelated parts
and makes it more obvious what the interactions between all the
parts are.
No functional changes, just moving code around.
Simon Ser
Alexander Orzechowski
Isaac Freund
Manuel Stoeckl