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vm_tools: sommelier: update linux-dmabuf-unstable-v1.xml to version 4
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BUG=b:234899270
TEST=vkcube in VM

Change-Id: Ie61a65faf177ed0ede2f705b9395a32601250514
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/4903156
Reviewed-by: Yiwei Zhang <[email protected]>
Tested-by: Ryan Neph <[email protected]>
Commit-Queue: Ryan Neph <[email protected]>
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Ryan Neph authored and Chromeos LUCI committed Nov 14, 2023
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Showing 1 changed file with 254 additions and 16 deletions.
270 changes: 254 additions & 16 deletions protocol/linux-dmabuf-unstable-v1.xml
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Original file line number Diff line number Diff line change
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DEALINGS IN THE SOFTWARE.
</copyright>

<interface name="zwp_linux_dmabuf_v1" version="3">
<interface name="zwp_linux_dmabuf_v1" version="4">
<description summary="factory for creating dmabuf-based wl_buffers">
Following the interfaces from:
https://www.khronos.org/registry/egl/extensions/EXT/EGL_EXT_image_dma_buf_import.txt
https://www.khronos.org/registry/EGL/extensions/EXT/EGL_EXT_image_dma_buf_import_modifiers.txt
and the Linux DRM sub-system's AddFb2 ioctl.

This interface offers ways to create generic dmabuf-based
wl_buffers. Immediately after a client binds to this interface,
the set of supported formats and format modifiers is sent with
'format' and 'modifier' events.
This interface offers ways to create generic dmabuf-based wl_buffers.

Clients can use the get_surface_feedback request to get dmabuf feedback
for a particular surface. If the client wants to retrieve feedback not
tied to a surface, they can use the get_default_feedback request.

The following are required from clients:

Expand All @@ -54,6 +56,12 @@
at any time use those fds to import the dmabuf into any kernel
sub-system that might accept it.

However, when the underlying graphics stack fails to deliver the
promise, because of e.g. a device hot-unplug which raises internal
errors, after the wl_buffer has been successfully created the
compositor must not raise protocol errors to the client when dmabuf
import later fails.

To create a wl_buffer from one or more dmabufs, a client creates a
zwp_linux_dmabuf_params_v1 object with a zwp_linux_dmabuf_v1.create_params
request. All planes required by the intended format are added with
Expand All @@ -75,6 +83,9 @@
client. If the client uses a failed wl_buffer as an argument to any
request, the behaviour is compositor implementation-defined.

For all DRM formats and unless specified in another protocol extension,
pre-multiplied alpha is used for pixel values.

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.
Expand Down Expand Up @@ -113,10 +124,9 @@
For the definition of the format codes, see the
zwp_linux_buffer_params_v1::create request.

Warning: the 'format' event is likely to be deprecated and replaced
with the 'modifier' event introduced in zwp_linux_dmabuf_v1
version 3, described below. Please refrain from using the information
received from this event.
Starting version 4, the format event is deprecated and must not be
sent by compositors. Instead, use get_default_feedback or
get_surface_feedback.
</description>
<arg name="format" type="uint" summary="DRM_FORMAT code"/>
</event>
Expand All @@ -129,18 +139,58 @@
binds to this interface. A roundtrip after binding guarantees that
the client has received all supported format-modifier pairs.

For legacy support, DRM_FORMAT_MOD_INVALID (that is, modifier_hi ==
0x00ffffff and modifier_lo == 0xffffffff) is allowed in this event.
It indicates that the server can support the format with an implicit
modifier. When a plane has DRM_FORMAT_MOD_INVALID as its modifier, it
is as if no explicit modifier is specified. The effective modifier
will be derived from the dmabuf.

A compositor that sends valid modifiers and DRM_FORMAT_MOD_INVALID for
a given format supports both explicit modifiers and implicit modifiers.

For the definition of the format and modifier codes, see the
zwp_linux_buffer_params_v1::create request.
zwp_linux_buffer_params_v1::create and zwp_linux_buffer_params_v1::add
requests.

Starting version 4, the modifier event is deprecated and must not be
sent by compositors. Instead, use get_default_feedback or
get_surface_feedback.
</description>
<arg name="format" type="uint" summary="DRM_FORMAT code"/>
<arg name="modifier_hi" type="uint"
summary="high 32 bits of layout modifier"/>
<arg name="modifier_lo" type="uint"
summary="low 32 bits of layout modifier"/>
</event>

<!-- Version 4 additions -->

<request name="get_default_feedback" since="4">
<description summary="get default feedback">
This request creates a new wp_linux_dmabuf_feedback object not bound
to a particular surface. This object will deliver feedback about dmabuf
parameters to use if the client doesn't support per-surface feedback
(see get_surface_feedback).
</description>
<arg name="id" type="new_id" interface="zwp_linux_dmabuf_feedback_v1"/>
</request>

<request name="get_surface_feedback" since="4">
<description summary="get feedback for a surface">
This request creates a new wp_linux_dmabuf_feedback object for the
specified wl_surface. This object will deliver feedback about dmabuf
parameters to use for buffers attached to this surface.

If the surface is destroyed before the wp_linux_dmabuf_feedback object,
the feedback object becomes inert.
</description>
<arg name="id" type="new_id" interface="zwp_linux_dmabuf_feedback_v1"/>
<arg name="surface" type="object" interface="wl_surface"/>
</request>
</interface>

<interface name="zwp_linux_buffer_params_v1" version="3">
<interface name="zwp_linux_buffer_params_v1" version="4">
<description summary="parameters for creating a dmabuf-based wl_buffer">
This temporary object is a collection of dmabufs and other
parameters that together form a single logical buffer. The temporary
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compression, etc. driver-specific modifications to the base format
defined by the DRM fourcc code.

Starting from version 4, the invalid_format protocol error is sent if
the format + modifier pair was not advertised as supported.

This request raises the PLANE_IDX error if plane_idx is too large.
The error PLANE_SET is raised if attempting to set a plane that
was already set.
Expand All @@ -211,7 +264,7 @@
summary="low 32 bits of layout modifier"/>
</request>

<enum name="flags">
<enum name="flags" bitfield="true">
<entry name="y_invert" value="1" summary="contents are y-inverted"/>
<entry name="interlaced" value="2" summary="content is interlaced"/>
<entry name="bottom_first" value="4" summary="bottom field first"/>
Expand Down Expand Up @@ -282,7 +335,7 @@
<arg name="width" type="int" summary="base plane width in pixels"/>
<arg name="height" type="int" summary="base plane height in pixels"/>
<arg name="format" type="uint" summary="DRM_FORMAT code"/>
<arg name="flags" type="uint" summary="see enum flags"/>
<arg name="flags" type="uint" enum="flags" summary="see enum flags"/>
</request>

<event name="created">
Expand All @@ -291,7 +344,7 @@
successful. It provides the new wl_buffer referencing the dmabuf(s).

Upon receiving this event, the client should destroy the
zlinux_dmabuf_params object.
zwp_linux_buffer_params_v1 object.
</description>
<arg name="buffer" type="new_id" interface="wl_buffer"
summary="the newly created wl_buffer"/>
Expand All @@ -304,7 +357,7 @@
has not been fulfilled.

Upon receiving this event, the client should destroy the
zlinux_buffer_params object.
zwp_linux_buffer_params_v1 object.
</description>
</event>

Expand Down Expand Up @@ -340,9 +393,194 @@
<arg name="width" type="int" summary="base plane width in pixels"/>
<arg name="height" type="int" summary="base plane height in pixels"/>
<arg name="format" type="uint" summary="DRM_FORMAT code"/>
<arg name="flags" type="uint" summary="see enum flags"/>
<arg name="flags" type="uint" enum="flags" summary="see enum flags"/>
</request>
</interface>

<interface name="zwp_linux_dmabuf_feedback_v1" version="4">
<description summary="dmabuf feedback">
This object advertises dmabuf parameters feedback. This includes the
preferred devices and the supported formats/modifiers.

The parameters are sent once when this object is created and whenever they
change. The done event is always sent once after all parameters have been
sent. When a single parameter changes, all parameters are re-sent by the
compositor.

Compositors can re-send the parameters when the current client buffer
allocations are sub-optimal. Compositors should not re-send the
parameters if re-allocating the buffers would not result in a more optimal
configuration. In particular, compositors should avoid sending the exact
same parameters multiple times in a row.

The tranche_target_device and tranche_formats events are grouped by
tranches of preference. For each tranche, a tranche_target_device, one
tranche_flags and one or more tranche_formats events are sent, followed
by a tranche_done event finishing the list. The tranches are sent in
descending order of preference. All formats and modifiers in the same
tranche have the same preference.

To send parameters, the compositor sends one main_device event, tranches
(each consisting of one tranche_target_device event, one tranche_flags
event, tranche_formats events and then a tranche_done event), then one
done event.
</description>

<request name="destroy" type="destructor">
<description summary="destroy the feedback object">
Using this request a client can tell the server that it is not going to
use the wp_linux_dmabuf_feedback object anymore.
</description>
</request>

<event name="done">
<description summary="all feedback has been sent">
This event is sent after all parameters of a wp_linux_dmabuf_feedback
object have been sent.

This allows changes to the wp_linux_dmabuf_feedback parameters to be
seen as atomic, even if they happen via multiple events.
</description>
</event>

<event name="format_table">
<description summary="format and modifier table">
This event provides a file descriptor which can be memory-mapped to
access the format and modifier table.

The table contains a tightly packed array of consecutive format +
modifier pairs. Each pair is 16 bytes wide. It contains a format as a
32-bit unsigned integer, followed by 4 bytes of unused padding, and a
modifier as a 64-bit unsigned integer. The native endianness is used.

The client must map the file descriptor in read-only private mode.

Compositors are not allowed to mutate the table file contents once this
event has been sent. Instead, compositors must create a new, separate
table file and re-send feedback parameters. Compositors are allowed to
store duplicate format + modifier pairs in the table.
</description>
<arg name="fd" type="fd" summary="table file descriptor"/>
<arg name="size" type="uint" summary="table size, in bytes"/>
</event>

<event name="main_device">
<description summary="preferred main device">
This event advertises the main device that the server prefers to use
when direct scan-out to the target device isn't possible. The
advertised main device may be different for each
wp_linux_dmabuf_feedback object, and may change over time.

There is exactly one main device. The compositor must send at least
one preference tranche with tranche_target_device equal to main_device.

Clients need to create buffers that the main device can import and
read from, otherwise creating the dmabuf wl_buffer will fail (see the
wp_linux_buffer_params.create and create_immed requests for details).
The main device will also likely be kept active by the compositor,
so clients can use it instead of waking up another device for power
savings.

In general the device is a DRM node. The DRM node type (primary vs.
render) is unspecified. Clients must not rely on the compositor sending
a particular node type. Clients cannot check two devices for equality
by comparing the dev_t value.

If explicit modifiers are not supported and the client performs buffer
allocations on a different device than the main device, then the client
must force the buffer to have a linear layout.
</description>
<arg name="device" type="array" summary="device dev_t value"/>
</event>

<event name="tranche_done">
<description summary="a preference tranche has been sent">
This event splits tranche_target_device and tranche_formats events in
preference tranches. It is sent after a set of tranche_target_device
and tranche_formats events; it represents the end of a tranche. The
next tranche will have a lower preference.
</description>
</event>

<event name="tranche_target_device">
<description summary="target device">
This event advertises the target device that the server prefers to use
for a buffer created given this tranche. The advertised target device
may be different for each preference tranche, and may change over time.

There is exactly one target device per tranche.

The target device may be a scan-out device, for example if the
compositor prefers to directly scan-out a buffer created given this
tranche. The target device may be a rendering device, for example if
the compositor prefers to texture from said buffer.

The client can use this hint to allocate the buffer in a way that makes
it accessible from the target device, ideally directly. The buffer must
still be accessible from the main device, either through direct import
or through a potentially more expensive fallback path. If the buffer
can't be directly imported from the main device then clients must be
prepared for the compositor changing the tranche priority or making
wl_buffer creation fail (see the wp_linux_buffer_params.create and
create_immed requests for details).

If the device is a DRM node, the DRM node type (primary vs. render) is
unspecified. Clients must not rely on the compositor sending a
particular node type. Clients cannot check two devices for equality by
comparing the dev_t value.

This event is tied to a preference tranche, see the tranche_done event.
</description>
<arg name="device" type="array" summary="device dev_t value"/>
</event>

<event name="tranche_formats">
<description summary="supported buffer format modifier">
This event advertises the format + modifier combinations that the
compositor supports.

It carries an array of indices, each referring to a format + modifier
pair in the last received format table (see the format_table event).
Each index is a 16-bit unsigned integer in native endianness.

For legacy support, DRM_FORMAT_MOD_INVALID is an allowed modifier.
It indicates that the server can support the format with an implicit
modifier. When a buffer has DRM_FORMAT_MOD_INVALID as its modifier, it
is as if no explicit modifier is specified. The effective modifier
will be derived from the dmabuf.

A compositor that sends valid modifiers and DRM_FORMAT_MOD_INVALID for
a given format supports both explicit modifiers and implicit modifiers.

Compositors must not send duplicate format + modifier pairs within the
same tranche or across two different tranches with the same target
device and flags.

This event is tied to a preference tranche, see the tranche_done event.

For the definition of the format and modifier codes, see the
wp_linux_buffer_params.create request.
</description>
<arg name="indices" type="array" summary="array of 16-bit indexes"/>
</event>

<enum name="tranche_flags" bitfield="true">
<entry name="scanout" value="1" summary="direct scan-out tranche"/>
</enum>

<event name="tranche_flags">
<description summary="tranche flags">
This event sets tranche-specific flags.

The scanout flag is a hint that direct scan-out may be attempted by the
compositor on the target device if the client appropriately allocates a
buffer. How to allocate a buffer that can be scanned out on the target
device is implementation-defined.

This event is tied to a preference tranche, see the tranche_done event.
</description>
<arg name="flags" type="uint" enum="tranche_flags" summary="tranche flags"/>
</event>
</interface>

</protocol>

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