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https://gitlab.freedesktop.org/wayland/weston
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26d5102957
Weston extension to assure clients that the dmabuf buffer will be forwarded directly to the display controller. Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
83 lines
3.9 KiB
XML
83 lines
3.9 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<protocol name="weston_direct_display">
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<copyright>
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Copyright © 2019 Collabora Ltd.
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice (including the next
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paragraph) shall be included in all copies or substantial portions of the
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Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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</copyright>
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<interface name="weston_direct_display_v1" version="1">
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<description summary="weston direct display">
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Weston extension to instruct the compositor to avoid any import
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of the dmabuf created by 'linux-dmabuf' protocol other than the display
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controller.
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Compositors are already going to use direct scan-out as much as possible but
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there's no assurance that while doing so, they won't first import the dmabuf
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in to the GPU. This extension assures the client that the compositor will
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never attempt to import in to the GPU and pass it directly to the display
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controller.
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Clients can make use of this extension to pass the dmabuf buffer to the
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display controller, potentially increasing the performance and lowering the
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bandwidth usage.
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Lastly, clients can make use of this extension in tandem with content-protection
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one thus avoiding any GPU interaction and providing a secure-content path.
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Also, in some cases, the memory where dmabuf are allocated are in specially
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crafted memory zone which would be seen as an illegal memory access when the
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GPU will attempt to read it.
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WARNING: This interface by design might break screenshoting functionality
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as compositing might be involved while doing that. Also, do note, that in
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case the dmabufer provided can't be imported by KMS, the client connection
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will be terminated.
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WARNING: This extension requires 'linux-dmabuf' protocol and
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'zwp_linux_buffer_params_v1' be already created by 'zwp_linux_buffer_v1'.
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</description>
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<request name="enable">
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<description summary="forward buffer to display controller">
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This request tells the compositor not to import the dmabuf to the GPU
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in order to bypass it entirely, such that the buffer will be directly
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scanned-out by the display controller. If HW is not capable/or there
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aren't any available resources to directly scan-out the buffer, a
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placeholder should be installed in-place by the compositor. The
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compositor may perform checks on the dmabuf and refuse to create a
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wl_buffer if the dmabuf seems unusable for being used directly.
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Assumes that 'zwp_linux_buffer_params_v1' was already created
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by 'zwp_linux_dmabuf_v1_create_params'.
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</description>
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<arg name="dmabuf" type="object" interface="zwp_linux_buffer_params_v1"
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summary="enable direct-display for dmabuf buffer"/>
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</request>
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<request name="destroy" type="destructor">
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<description summary="destroy factory object">
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Destroys the factory object, but does not affect any other objects.
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</description>
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</request>
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</interface>
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</protocol>
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