On Tue, Sep 19, 2017 at 6:46 PM, Daniel Stone <dani...@collabora.com> wrote: > Signed-off-by: Daniel Stone <dani...@collabora.com> > --- > Makefile.am | 1 + > unstable/linux-explicit-synchronization/README | 5 + > .../linux-explicit-synchronization-unstable-v1.xml | 208 > +++++++++++++++++++++ > 3 files changed, 214 insertions(+) > create mode 100644 unstable/linux-explicit-synchronization/README > create mode 100644 > unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml > > diff --git a/Makefile.am b/Makefile.am > index 5b5ae96..941692c 100644 > --- a/Makefile.am > +++ b/Makefile.am > @@ -15,6 +15,7 @@ unstable_protocols = > \ > > unstable/xwayland-keyboard-grab/xwayland-keyboard-grab-unstable-v1.xml \ > > unstable/keyboard-shortcuts-inhibit/keyboard-shortcuts-inhibit-unstable-v1.xml > \ > unstable/xdg-output/xdg-output-unstable-v1.xml > \ > + > unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml > \ > $(NULL) > > stable_protocols = > \ > diff --git a/unstable/linux-explicit-synchronization/README > b/unstable/linux-explicit-synchronization/README > new file mode 100644 > index 0000000..fac116f > --- /dev/null > +++ b/unstable/linux-explicit-synchronization/README > @@ -0,0 +1,5 @@ > +Linux explicit synchronization (dma-fence) protocol > + > +Maintainers: > +David Reveman <reve...@chromium.org> > +Daniel Stone <dani...@collabora.com> > diff --git > a/unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml > > b/unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml > new file mode 100644 > index 0000000..4a6636e > --- /dev/null > +++ > b/unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml > @@ -0,0 +1,208 @@ > +<?xml version="1.0" encoding="UTF-8"?> > +<protocol name="zwp_linux_explicit_synchronization_unstable_v1"> > + > + <copyright> > + Copyright 2016 The Chromium Authors. > + Copyright 2017 Intel Corporation > + > + Permission is hereby granted, free of charge, to any person obtaining a > + copy of this software and associated documentation files (the > "Software"), > + to deal in the Software without restriction, including without limitation > + the rights to use, copy, modify, merge, publish, distribute, sublicense, > + and/or sell copies of the Software, and to permit persons to whom the > + Software is furnished to do so, subject to the following conditions: > + > + The above copyright notice and this permission notice (including the next > + paragraph) shall be included in all copies or substantial portions of the > + Software. > + > + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS > OR > + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, > + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL > + THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR > OTHER > + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING > + FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > + DEALINGS IN THE SOFTWARE. > + </copyright> > + > + <interface name="zwp_linux_explicit_synchronization_v1" version="1"> > + <description summary="protocol for providing explicit synchronization"> > + This global is a factory interface, allowing clients to request > + explicit synchronization for buffers on a per-surface basis. > + > + See zwp_surface_synchronization_v1 for more information. > + > + This interface is derived from Chromium's > + zcr_linux_explicit_synchronization_v1. > + > + Warning! The protocol described in this file is experimental and > + backward incompatible changes may be made. Backward compatible changes > + may be added together with the corresponding interface version bump. > + Backward incompatible changes are done by bumping the version number in > + the protocol and interface names and resetting the interface version. > + Once the protocol is to be declared stable, the 'z' prefix and the > + version number in the protocol and interface names are removed and the > + interface version number is reset. > + </description> > + > + <request name="destroy" type="destructor"> > + <description summary="destroy explicit synchronization factory object"> > + Destroy this explicit synchronization factory object. Other objects, > + including zwp_surface_synchronization_v1 objects created by this > + factory, shall not be affected by this request. > + </description> > + </request> > + > + <enum name="error"> > + <entry name="synchronization_exists" value="0" > + summary="the surface already has a synchronization object > associated"/> > + </enum> > + > + <request name="get_synchronization"> > + <description summary="extend surface interface for explicit > synchronization"> > + Instantiate an interface extension for the given wl_surface to > + provide explicit synchronization. > + > + If the given wl_surface already has an explicit synchronization object > + associated, the synchronization_exists protocol error is raised. > + </description> > + > + <arg name="id" type="new_id" interface="zwp_surface_synchronization_v1" > + summary="the new synchronization interface id"/> > + <arg name="surface" type="object" interface="wl_surface" > + summary="the surface"/> > + </request> > + </interface> > + > + <interface name="zwp_surface_synchronization_v1" version="1"> > + <description summary="per-surface explicit synchronization support"> > + This object implements per-surface explicit synchronization. > + > + Explicit synchronization refers to co-ordination of pipelined > + operations performed on buffers. Most GPU clients will schedule > + an asynchronous operation to render to the buffer, then immediately > + send the buffer to the compositor to be attached to a surface. > + Ensuring that the rendering operation is complete before the > + compositor displays the buffer is an implementation detail handled > + by either the kernel or userspace graphics driver. This is referred > + to as 'implicit synchronization'. > + > + By contrast, explicit synchronization takes dma_fence objects as a > + marker of when the asynchronous operations are complete. The fence > + provided by the client will be waited on before the compositor > + accesses the buffer. Conversely, in place of wl_buffer.release > + events, the Wayland server will inform the client when the buffer > + can be destructively accessed through a zwp_buffer_release_v1 > + object. > + > + This interface cannot be instantiated multiple times for a single > + surface, and as such should only be used by the component which > + performs the wl_surface.attach request. Whenever control of > + buffer attachments is released, the releasing component should > + ensure it destroys the zwp_surface_synchronization_v1 object. > + > + It is illegal to destroy a zwp_surface_synchronization_v1 object > + after its wl_surface has been destroyed. > + </description> > + > + <request name="destroy" type="destructor"> > + <description summary="destroy synchronization object"> > + Destroy this explicit synchronization object. > + > + zwp_buffer_release_v1 objects created by this object are not affected > + by this request. > + </description> > + </request> > + > + <enum name="error"> > + <entry name="invalid_fence" value="0" > + summary="the fence specified by the client could not be > imported"/> > + <entry name="duplicate_fence" value="1" > + summary="multiple fences added for a single surface commit"/> > + <entry name="duplicate_release" value="2" > + summary="multiple releases added for a single surface commit"/> > + </enum> > + > + <request name="set_acquire_fence"> > + <description summary="set the acquire fence"> > + Set the acquire fence that must be signaled before the compositor > + may sample from the buffer attached with wl_buffer_attach. The fence > + is a dma_fence kernel object. > + > + The acquire fence is double-buffered state, and will be applied on > + the next wl_surface.commit request for the associated surface. > + > + If the fence could not be imported, an INVALID_FENCE error is signaled > + to the client. > + > + If a fence has already been attached during the same commit cycle, > + a DUPLICATE_FENCE error is signaled to the client. > + </description> > + <arg name="fd" type="fd" summary="acquire fence fd"/> > + </request> > + > + <request name="get_release"> > + <description summary="release fence for last-attached buffer"> > + Create a listener for the release of the buffer attached by the > + client with wl_buffer.attach. See zwp_buffer_release_v1 > + documentation for more information. > + > + The release object is double-buffered state, and will be applied > + on the next wl_surface.commit request for the associated surface. > + > + If a zwp_buffer_release_v1 object has already been requested for > + the surface in the same commit cycle, a DUPLICATE_RELEASE error > + is signaled to the client. > + </description> > + > + <arg name="release" type="new_id" interface="zwp_buffer_release_v1" > + summary="new zwp_buffer_release_v1 object"/> > + </request> > + </interface> > + > + <interface name="zwp_buffer_release_v1" version="1"> > + <description summary="buffer release explicit synchronization"> > + This object is instantiated in response to a > + zwp_surface_synchronization_v1 request. > + > + It provides an alternative to wl_buffer.release events, providing > + a unique release from a single wl_surface.commit request. The release > + event also supports explicit synchronization, providing a fence FD > + where relevant for the client to synchronize against before reusing > + the buffer. > + > + This event does not replace wl_buffer.release events; servers are still > + required to send those events. > + </description> > + > + <request name="destroy" type="destructor"> > + <description summary="destroy buffer release synchronization object"> > + Destroy this buffer release explicit synchronization object. The > object > + may be destroyed at any time. > + </description> > + </request> > + > + <event name="fenced_release"> > + <description summary="release buffer with fence"> > + Sent when the compositor has finalised its usage of the associated > + buffer, providing a dma_fence which will be signaled when all > + operations by the compositor on that buffer have finished. > + > + Clients must not perform any destructive operations (e.g. clearing or > + rendering) on the buffer until that fence has passed. They may, > + however, destroy the wl_buffer object. > + </description> > + <arg name="fence" type="fd" summary="fence for last operation on > buffer"/> > + </event> > + > + <event name="immediate_release"> > + <description summary="release buffer immediately"> > + Sent when the compositor has finalised its usage of the associated > + buffer, and either performed no operations using it, or has a > + guarantee that all its operations have finished and no more external > + effects will be observed from these operations. > + </description> > + </event> > + </interface> > + > +</protocol> > -- > 2.14.1
On a related subject, there was discussion back at https://lists.freedesktop.org/archives/wayland-devel/2013-September/011091.html that acknowledged a longstanding bug where wl_buffer::release events are starved indefinitely in the outbound server socket if there doesn't happen to be any frame callback installed. That discussion petered out, but it looked like there was a consensus that the issue should be fixed (post the WL_BUFFER_RELEASE immediately rather than queue if no frame callbacks attached). That seems like a good issue to get closed up. Any objections to reviving the patch along the lines that Pekka suggested? _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
