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presentation-time: Describe the refresh cycle events

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Signed-off-by: Sebastian Wick <sebastian.wick@redhat.com>
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Sebastian Wick 2023-04-04 03:36:01 +02:00
parent 54e66f28c5
commit 2c3fc18fb4
1 changed files with 49 additions and 24 deletions
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73
stable/presentation-time/presentation-time.xml
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@ -376,8 +376,16 @@
never be decreased below duration_min and can never be
increased beyond duration_max.
The buffer_latching argument describes when the buffer latching
of a refresh cycle happens relative to the commit latching. See
the latching event for more information.
The presentation argument describes when the presentation of a
refresh cycle happens relative to the commit latching. See the
latching event for more information.
This event indicates a discontinuity and the discontinuity flag
in the latching event is set.
of the next latching event is set.
The compositor sends this event when the client binds to the
refresh_cycle interface.
@ -394,6 +402,10 @@
summary="the maximum increase of the duration per refresh cycle in nanoseconds"/>
<arg name="ramp_down" type="uint"
summary="the maximum decrease of the duration per refresh cycle in nanoseconds"/>
<arg name="buffer_latching" type="uint"
summary="the time of the buffer latching in nanoseconds after the commit latching"/>
<arg name="presentation" type="uint"
summary="the time of the presentation in nanoseconds after the commit latching"/>
</event>
<enum name="latching_flags" bitfield="true">
@ -415,44 +427,57 @@
<event name="latching">
<description summary="latching event">
The latching event is sent no earlier than the compositor
deciding which commits will be chosen for the next
presentation, but as close to it as possible.
Each refresh cycle consists of a number of events in order: the
commit latching of the previous refresh cycle, the commit
latching of the current cycle, the buffer latching and the
presentation.
The exact time of this event is recorded in the commit latching
timestamp (commit_tv_sec_hi/lo, commit_tv_nsec).
The commit latching indicates the start of a new refresh cycle.
Two refresh cycles overlap between the commit latching and the
presentation. The buffer latching can be at the same time as
the commit latching.
The buffer latching timestamp (buffer_tv_sec_hi/lo,
buffer_tv_nsec) describes when all the fences of buffers
attached to surfaces of a commit must be signaled in order to
get presented on the refresh cycle of this latching event.
The time between two commit latching events is the duration of
the refresh cycle and describes the update frequency.
For the interpretation of the timestamps, see
presentation.clock_id.
If a content update is supposed to land on a certain refresh
cycle then the content update must be committed before the
commit latching and the buffers of the content update must be
ready before the buffer latching.
A buffer is considered ready if there are no fences attached to
it or if all the explicit and implicit fences attached to it
are signaled.
If a content update landed on a refresh cycle then it is
considered for presentation by the compositor on this or any
of the following refresh cycles.
This latching event is sent no earlier than the commit latching
but as close to it as possible.
The exact time of the commit latching is recorded in the
timestamp (commit_tv_sec_hi/lo, commit_tv_nsec). For the
interpretation of the timestamp, see presentation.clock_id.
The 64-bit value combined from seq_hi and seq_lo is the value
of the output's vertical retrace counter of the following
of the output's vertical retrace counter of the refresh cycle's
presentation. This value is compatible with seq_hi and seq_lo
from presentation_feedback.presented.
The time of the buffer latching and presentation relative to the
commit latching is sent in the state event.
</description>
<arg name="commit_tv_sec_hi" type="uint"
<arg name="tv_sec_hi" type="uint"
summary="high 32 bits of the seconds part of the commit latching timestamp"/>
<arg name="commit_tv_sec_lo" type="uint"
<arg name="tv_sec_lo" type="uint"
summary="low 32 bits of the seconds part of the commit latching timestamp"/>
<arg name="commit_tv_nsec" type="uint"
<arg name="tv_nsec" type="uint"
summary="nanoseconds part of the commit latching timestamp"/>
<arg name="buffer_tv_sec_hi" type="uint"
summary="high 32 bits of the seconds part of the buffer latching timestamp"/>
<arg name="buffer_tv_sec_lo" type="uint"
summary="low 32 bits of the seconds part of the buffer latching timestamp"/>
<arg name="buffer_tv_nsec" type="uint"
summary="nanoseconds part of the buffer latching timestamp"/>
<arg name="seq_hi" type="uint"
summary="high 32 bits of refresh counter"/>
<arg name="seq_lo" type="uint"
summary="low 32 bits of refresh counter"/>
<arg name="seq_lo" type="uint"
summary="low 32 bits of refresh counter"/>
<arg name="flags" type="uint" enum="latching_flags"
summary="combination of 'latching_flags' values"/>
</event>