Implement the set_acquire_fence request of the
zwp_surface_synchronization_v1 interface.
The implementation uses the acquire fence in two ways:
1. If the associated buffer is used as GL render source, an
EGLSyncKHR is created from the fence and used to synchronize
access.
2. If the associated buffer is used as a plane framebuffer,
the acquire fence is treated as an in-fence for the atomic
commit operation. If in-fences are not supported and the buffer
has an acquire fence, we don't consider it for plane placement.
If the used compositor/renderer doesn't support explicit
synchronization, we don't advertise the protocol at all. Currently only
the DRM and X11 backends when using the GL renderer advertise the
protocol for production use.
Issues for discussion
---------------------
a. Currently, a server-side wait of EGLSyncKHR is performed before
using the EGLImage/texture during rendering. Unfortunately, it's not clear
from the specs whether this is generally safe to do, or we need to
sync before glEGLImageTargetTexture2DOES. The exception is
TEXTURE_EXTERNAL_OES where the spec mentions it's enough to sync
and then glBindTexture for any changes to take effect.
Changes in v5:
- Meson support.
- Make explicit sync server error reporting more generic, supporting
all explicit sync related interfaces not just
wp_linux_surface_synchronization.
- Fix typo in warning for missing EGL_KHR_wait_sync extension.
- Support minor version 2 of the explicit sync protocol (i.e., support
fences for opaque EGL buffers).
Changes in v4:
- Introduce and use fd_clear and and fd_move helpers.
- Don't check for a valid buffer when updating surface acquire fence fd
from state.
- Assert that pending state acquire fence fd is always clear
after a commit.
- Clarify that WESTON_CAP_EXPLICIT_SYNC applies to just the
renderer.
- Check for EGL_KHR_wait_sync before using eglWaitSyncKHR.
- Dup the acquire fence before passing to EGL.
Changes in v3:
- Keep acquire_fence_fd in surface instead of buffer.
- Clarify that WESTON_CAP_EXPLICIT_SYNC applies to both backend and
renderer.
- Move comment about non-ownership of in_fence_fd to struct
drm_plane_state definition.
- Assert that we don't try to use planes with in-fences when using the
legacy KMS API.
- Remove unnecessary info from wayland error messages.
- Handle acquire fence for subsurface commits.
- Guard against self-update in fd_update.
- Disconnect the client if acquire fence EGLSyncKHR creation or wait
fails.
- Use updated protocol interface names.
- User correct format specifier for resource ids.
- Advertise protocol for X11 backend with GL renderer.
Changes in v2:
- Remove sync file wait fallbacks.
- Raise UNSUPPORTED_BUFFER error at commit if we have an acquire
fence, but the committed buffer is not a valid linux_dmabuf.
- Don't put buffers with in-fences on planes that don't support
in-fences.
- Don't advertise explicit sync protocol if backend does not
support explicit sync.
Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
acff29b3b3