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<?xml version="1.0" encoding="UTF-8"?>
<protocol name="weston_direct_display">
<copyright>
Copyright © 2019 Collabora Ltd.
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="weston_direct_display_v1" version="1">
<description summary="weston direct display">
Weston extension to instruct the compositor to avoid any import
of the dmabuf created by 'linux-dmabuf' protocol other than the display
controller.
Compositors are already going to use direct scan-out as much as possible but
there's no assurance that while doing so, they won't first import the dmabuf
in to the GPU. This extension assures the client that the compositor will
never attempt to import in to the GPU and pass it directly to the display
controller.
Clients can make use of this extension to pass the dmabuf buffer to the
display controller, potentially increasing the performance and lowering the
bandwidth usage.
Lastly, clients can make use of this extension in tandem with content-protection
one thus avoiding any GPU interaction and providing a secure-content path.
Also, in some cases, the memory where dmabuf are allocated are in specially
crafted memory zone which would be seen as an illegal memory access when the
GPU will attempt to read it.
WARNING: This interface by design might break screenshoting functionality
as compositing might be involved while doing that. Also, do note, that in
case the dmabufer provided can't be imported by KMS, the client connection
will be terminated.
WARNING: This extension requires 'linux-dmabuf' protocol and
'zwp_linux_buffer_params_v1' be already created by 'zwp_linux_buffer_v1'.
</description>
<request name="enable">
<description summary="forward buffer to display controller">
This request tells the compositor not to import the dmabuf to the GPU
in order to bypass it entirely, such that the buffer will be directly
scanned-out by the display controller. If HW is not capable/or there
aren't any available resources to directly scan-out the buffer, a
placeholder should be installed in-place by the compositor. The
compositor may perform checks on the dmabuf and refuse to create a
wl_buffer if the dmabuf seems unusable for being used directly.
Assumes that 'zwp_linux_buffer_params_v1' was already created
by 'zwp_linux_dmabuf_v1_create_params'.
</description>
<arg name="dmabuf" type="object" interface="zwp_linux_buffer_params_v1"
summary="enable direct-display for dmabuf buffer"/>
</request>
<request name="destroy" type="destructor">
<description summary="destroy factory object">
Destroys the factory object, but does not affect any other objects.
</description>
</request>
</interface>
</protocol>
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