363 lines
18 KiB
XML
363 lines
18 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<protocol name="linux_dmabuf_unstable_v1">
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<copyright>
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Copyright © 2014, 2015 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="zwp_linux_dmabuf_v1" version="3">
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<description summary="factory for creating dmabuf-based wl_buffers">
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Following the interfaces from:
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https://www.khronos.org/registry/egl/extensions/EXT/EGL_EXT_image_dma_buf_import.txt
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https://www.khronos.org/registry/EGL/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt
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and the Linux DRM sub-system's AddFb2 ioctl.
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This interface offers ways to create generic dmabuf-based
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wl_buffers. Immediately after a client binds to this interface,
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the set of supported formats and format modifiers is sent with
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'format' and 'modifier' events.
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The following are required from clients:
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- Clients must ensure that either all data in the dma-buf is
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coherent for all subsequent read access or that coherency is
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correctly handled by the underlying kernel-side dma-buf
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implementation.
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- Don't make any more attachments after sending the buffer to the
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compositor. Making more attachments later increases the risk of
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the compositor not being able to use (re-import) an existing
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dmabuf-based wl_buffer.
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The underlying graphics stack must ensure the following:
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- The dmabuf file descriptors relayed to the server will stay valid
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for the whole lifetime of the wl_buffer. This means the server may
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at any time use those fds to import the dmabuf into any kernel
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sub-system that might accept it.
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To create a wl_buffer from one or more dmabufs, a client creates a
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zwp_linux_dmabuf_params_v1 object with a zwp_linux_dmabuf_v1.create_params
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request. All planes required by the intended format are added with
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the 'add' request. Finally, a 'create' or 'create_immed' request is
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issued, which has the following outcome depending on the import success.
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The 'create' request,
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- on success, triggers a 'created' event which provides the final
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wl_buffer to the client.
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- on failure, triggers a 'failed' event to convey that the server
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cannot use the dmabufs received from the client.
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For the 'create_immed' request,
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- on success, the server immediately imports the added dmabufs to
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create a wl_buffer. No event is sent from the server in this case.
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- on failure, the server can choose to either:
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- terminate the client by raising a fatal error.
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- mark the wl_buffer as failed, and send a 'failed' event to the
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client. If the client uses a failed wl_buffer as an argument to any
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request, the behaviour is compositor implementation-defined.
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Warning! The protocol described in this file is experimental and
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backward incompatible changes may be made. Backward compatible changes
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may be added together with the corresponding interface version bump.
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Backward incompatible changes are done by bumping the version number in
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the protocol and interface names and resetting the interface version.
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Once the protocol is to be declared stable, the 'z' prefix and the
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version number in the protocol and interface names are removed and the
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interface version number is reset.
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</description>
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<request name="destroy" type="destructor">
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<description summary="unbind the factory">
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Objects created through this interface, especially wl_buffers, will
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remain valid.
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</description>
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</request>
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<request name="create_params">
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<description summary="create a temporary object for buffer parameters">
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This temporary object is used to collect multiple dmabuf handles into
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a single batch to create a wl_buffer. It can only be used once and
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should be destroyed after a 'created' or 'failed' event has been
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received.
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</description>
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<arg name="params_id" type="new_id" interface="zwp_linux_buffer_params_v1"
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summary="the new temporary"/>
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</request>
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<event name="format">
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<description summary="supported buffer format">
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This event advertises one buffer format that the server supports.
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All the supported formats are advertised once when the client
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binds to this interface. A roundtrip after binding guarantees
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that the client has received all supported formats.
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For the definition of the format codes, see the
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zwp_linux_buffer_params_v1::create request.
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Warning: the 'format' event is likely to be deprecated and replaced
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with the 'modifier' event introduced in zwp_linux_dmabuf_v1
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version 3, described below. Please refrain from using the information
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received from this event.
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</description>
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<arg name="format" type="uint" summary="DRM_FORMAT code"/>
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</event>
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<event name="modifier" since="3">
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<description summary="supported buffer format modifier">
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This event advertises the formats that the server supports, along with
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the modifiers supported for each format. All the supported modifiers
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for all the supported formats are advertised once when the client
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binds to this interface. A roundtrip after binding guarantees that
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the client has received all supported format-modifier pairs.
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For legacy support, DRM_FORMAT_MOD_INVALID (that is, modifier_hi ==
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0x00ffffff and modifier_lo == 0xffffffff) is allowed in this event.
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It indicates that the server can support the format with an implicit
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modifier. When a plane has DRM_FORMAT_MOD_INVALID as its modifier, it
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is as if no explicit modifier is specified. The effective modifier
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will be derived from the dmabuf.
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For the definition of the format and modifier codes, see the
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zwp_linux_buffer_params_v1::create and zwp_linux_buffer_params_v1::add
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requests.
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</description>
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<arg name="format" type="uint" summary="DRM_FORMAT code"/>
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<arg name="modifier_hi" type="uint"
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summary="high 32 bits of layout modifier"/>
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<arg name="modifier_lo" type="uint"
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summary="low 32 bits of layout modifier"/>
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</event>
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</interface>
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<interface name="zwp_linux_buffer_params_v1" version="3">
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<description summary="parameters for creating a dmabuf-based wl_buffer">
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This temporary object is a collection of dmabufs and other
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parameters that together form a single logical buffer. The temporary
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object may eventually create one wl_buffer unless cancelled by
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destroying it before requesting 'create'.
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Single-planar formats only require one dmabuf, however
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multi-planar formats may require more than one dmabuf. For all
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formats, an 'add' request must be called once per plane (even if the
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underlying dmabuf fd is identical).
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You must use consecutive plane indices ('plane_idx' argument for 'add')
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from zero to the number of planes used by the drm_fourcc format code.
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All planes required by the format must be given exactly once, but can
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be given in any order. Each plane index can be set only once.
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</description>
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<enum name="error">
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<entry name="already_used" value="0"
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summary="the dmabuf_batch object has already been used to create a wl_buffer"/>
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<entry name="plane_idx" value="1"
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summary="plane index out of bounds"/>
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<entry name="plane_set" value="2"
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summary="the plane index was already set"/>
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<entry name="incomplete" value="3"
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summary="missing or too many planes to create a buffer"/>
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<entry name="invalid_format" value="4"
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summary="format not supported"/>
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<entry name="invalid_dimensions" value="5"
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summary="invalid width or height"/>
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<entry name="out_of_bounds" value="6"
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summary="offset + stride * height goes out of dmabuf bounds"/>
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<entry name="invalid_wl_buffer" value="7"
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summary="invalid wl_buffer resulted from importing dmabufs via
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the create_immed request on given buffer_params"/>
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</enum>
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<request name="destroy" type="destructor">
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<description summary="delete this object, used or not">
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Cleans up the temporary data sent to the server for dmabuf-based
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wl_buffer creation.
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</description>
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</request>
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<request name="add">
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<description summary="add a dmabuf to the temporary set">
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This request adds one dmabuf to the set in this
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zwp_linux_buffer_params_v1.
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The 64-bit unsigned value combined from modifier_hi and modifier_lo
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is the dmabuf layout modifier. DRM AddFB2 ioctl calls this the
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fb modifier, which is defined in drm_mode.h of Linux UAPI.
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This is an opaque token. Drivers use this token to express tiling,
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compression, etc. driver-specific modifications to the base format
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defined by the DRM fourcc code.
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Warning: It should be an error if the format/modifier pair was not
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advertised with the modifier event. This is not enforced yet because
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some implementations always accept DRM_FORMAT_MOD_INVALID. Also
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version 2 of this protocol does not have the modifier event.
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This request raises the PLANE_IDX error if plane_idx is too large.
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The error PLANE_SET is raised if attempting to set a plane that
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was already set.
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</description>
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<arg name="fd" type="fd" summary="dmabuf fd"/>
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<arg name="plane_idx" type="uint" summary="plane index"/>
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<arg name="offset" type="uint" summary="offset in bytes"/>
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<arg name="stride" type="uint" summary="stride in bytes"/>
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<arg name="modifier_hi" type="uint"
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summary="high 32 bits of layout modifier"/>
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<arg name="modifier_lo" type="uint"
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summary="low 32 bits of layout modifier"/>
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</request>
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<enum name="flags">
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<entry name="y_invert" value="1" summary="contents are y-inverted"/>
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<entry name="interlaced" value="2" summary="content is interlaced"/>
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<entry name="bottom_first" value="4" summary="bottom field first"/>
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</enum>
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<request name="create">
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<description summary="create a wl_buffer from the given dmabufs">
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This asks for creation of a wl_buffer from the added dmabuf
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buffers. The wl_buffer is not created immediately but returned via
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the 'created' event if the dmabuf sharing succeeds. The sharing
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may fail at runtime for reasons a client cannot predict, in
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which case the 'failed' event is triggered.
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The 'format' argument is a DRM_FORMAT code, as defined by the
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libdrm's drm_fourcc.h. The Linux kernel's DRM sub-system is the
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authoritative source on how the format codes should work.
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The 'flags' is a bitfield of the flags defined in enum "flags".
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'y_invert' means the that the image needs to be y-flipped.
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Flag 'interlaced' means that the frame in the buffer is not
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progressive as usual, but interlaced. An interlaced buffer as
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supported here must always contain both top and bottom fields.
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The top field always begins on the first pixel row. The temporal
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ordering between the two fields is top field first, unless
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'bottom_first' is specified. It is undefined whether 'bottom_first'
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is ignored if 'interlaced' is not set.
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This protocol does not convey any information about field rate,
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duration, or timing, other than the relative ordering between the
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two fields in one buffer. A compositor may have to estimate the
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intended field rate from the incoming buffer rate. It is undefined
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whether the time of receiving wl_surface.commit with a new buffer
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attached, applying the wl_surface state, wl_surface.frame callback
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trigger, presentation, or any other point in the compositor cycle
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is used to measure the frame or field times. There is no support
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for detecting missed or late frames/fields/buffers either, and
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there is no support whatsoever for cooperating with interlaced
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compositor output.
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The composited image quality resulting from the use of interlaced
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buffers is explicitly undefined. A compositor may use elaborate
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hardware features or software to deinterlace and create progressive
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output frames from a sequence of interlaced input buffers, or it
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may produce substandard image quality. However, compositors that
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cannot guarantee reasonable image quality in all cases are recommended
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to just reject all interlaced buffers.
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Any argument errors, including non-positive width or height,
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mismatch between the number of planes and the format, bad
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format, bad offset or stride, may be indicated by fatal protocol
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errors: INCOMPLETE, INVALID_FORMAT, INVALID_DIMENSIONS,
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OUT_OF_BOUNDS.
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Dmabuf import errors in the server that are not obvious client
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bugs are returned via the 'failed' event as non-fatal. This
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allows attempting dmabuf sharing and falling back in the client
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if it fails.
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This request can be sent only once in the object's lifetime, after
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which the only legal request is destroy. This object should be
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destroyed after issuing a 'create' request. Attempting to use this
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object after issuing 'create' raises ALREADY_USED protocol error.
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It is not mandatory to issue 'create'. If a client wants to
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cancel the buffer creation, it can just destroy this object.
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</description>
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<arg name="width" type="int" summary="base plane width in pixels"/>
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<arg name="height" type="int" summary="base plane height in pixels"/>
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<arg name="format" type="uint" summary="DRM_FORMAT code"/>
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<arg name="flags" type="uint" summary="see enum flags"/>
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</request>
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<event name="created">
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<description summary="buffer creation succeeded">
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This event indicates that the attempted buffer creation was
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successful. It provides the new wl_buffer referencing the dmabuf(s).
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Upon receiving this event, the client should destroy the
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zlinux_dmabuf_params object.
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</description>
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<arg name="buffer" type="new_id" interface="wl_buffer"
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summary="the newly created wl_buffer"/>
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</event>
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<event name="failed">
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<description summary="buffer creation failed">
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This event indicates that the attempted buffer creation has
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failed. It usually means that one of the dmabuf constraints
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has not been fulfilled.
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Upon receiving this event, the client should destroy the
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zlinux_buffer_params object.
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</description>
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</event>
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<request name="create_immed" since="2">
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<description summary="immediately create a wl_buffer from the given
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dmabufs">
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This asks for immediate creation of a wl_buffer by importing the
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added dmabufs.
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In case of import success, no event is sent from the server, and the
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wl_buffer is ready to be used by the client.
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Upon import failure, either of the following may happen, as seen fit
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by the implementation:
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- the client is terminated with one of the following fatal protocol
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errors:
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- INCOMPLETE, INVALID_FORMAT, INVALID_DIMENSIONS, OUT_OF_BOUNDS,
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in case of argument errors such as mismatch between the number
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of planes and the format, bad format, non-positive width or
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height, or bad offset or stride.
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- INVALID_WL_BUFFER, in case the cause for failure is unknown or
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plaform specific.
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- the server creates an invalid wl_buffer, marks it as failed and
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sends a 'failed' event to the client. The result of using this
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invalid wl_buffer as an argument in any request by the client is
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defined by the compositor implementation.
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This takes the same arguments as a 'create' request, and obeys the
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same restrictions.
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</description>
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<arg name="buffer_id" type="new_id" interface="wl_buffer"
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summary="id for the newly created wl_buffer"/>
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<arg name="width" type="int" summary="base plane width in pixels"/>
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<arg name="height" type="int" summary="base plane height in pixels"/>
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<arg name="format" type="uint" summary="DRM_FORMAT code"/>
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<arg name="flags" type="uint" summary="see enum flags"/>
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</request>
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</interface>
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</protocol>
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