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Diffstat (limited to 'presentproto.txt')
| -rw-r--r-- | presentproto.txt | 109 |
1 files changed, 107 insertions, 2 deletions
diff --git a/presentproto.txt b/presentproto.txt index b474093..56c20d4 100644 --- a/presentproto.txt +++ b/presentproto.txt @@ -1,5 +1,5 @@ The Present Extension - Version 1.3 + Version 1.4 2023-06-13 Keith Packard @@ -63,7 +63,8 @@ PRESENTOPTION { PresentOptionAsync, PRESENTCAPABILITY { PresentCapabilityAsync, PresentCapabilityFence, PresentCapabilityUST, - PresentCapabilityAsyncMayTear } + PresentCapabilityAsyncMayTear, + PresentCapabilitySyncobj } PRESENTCOMPLETEKIND { PresentCompleteKindPixmap, PresentCompleteKindMSCNotify } @@ -359,6 +360,85 @@ The name of this extension is "Present" defined by the extension, but is expected to be on the order of milliseconds or less. + PresentCapabilitySyncobj means that the target device supports + explicit synchronization using timeline DRM synchronization + objects. See the PresentPixmapSynced request for details. + +┌─── + PresentPixmapSynced + window: WINDOW + pixmap: PIXMAP + serial: CARD32 + valid-area: REGION or None + update-area: REGION or None + x-off, y-off: INT16 + target-crtc: CRTC or None + acquire-syncobj: SYNCOBJ or None + release-syncobj: SYNCOBJ or None + acquire-point: CARD64 + release-point: CARD64 + options: SETofPRESENTOPTION + target-msc: CARD64 + divisor: CARD64 + remainder: CARD64 + notifies: LISTofPRESENTNOTIFY +└─── + Errors: Window, Pixmap, Match, Value + + Identical to the PresentPixmap request, except that instead of the + 'wait-fence' and 'idle-fence' arguments it accepts mandatory + 'acquire-syncobj' and 'release-syncobj' arguments, along with + corresponding acquire and release points, to be used for explicit + timeline-based GPU synchronization. The 'acquire-point' and + 'release-point' are assumed to correspond to timeline points on the + respective DRM syncobjs. + + The contents of the Pixmap will not be accessed by the server until the + 'acquire-point' on the acquire timeline has been signaled by the + client. The fence need not be submitted at the time the + PresentPixmapSynced request is issued. + + Once the 'release-point' on the release timeline has been signaled, the + client may assume that no further GPU or CPU access to the Pixmap by + the server will occur as part of the originating PresentPixmapSynced + request. Note that this is a stronger guarantee than what is provided + by the 'idle-fence' argument of the PresentPixmap request or the + delivery of a PresentIdleNotify event, as those do not necessarily + imply that the Pixmap is idle on the GPU. + + The server may wait for the acquire point and signal the release point + itself, as will typically happen if the request is executed by copying + the Pixmap's contents. Alternatively, it may forward the timelines, + acquire, and release points to an output sink directly, provided that + sink also supports explicit synchronization using DRM syncobjs. + + The server may signal the release point without waiting for the acquire + point if the Pixmap's contents are never accessed while servicing the + request. This may happen, for example, if a request is discarded due to + it being fully occluded by a later request. + + Beware that, if multiple Pixmaps are presented using the same release + timeline, the server makes no guarantees on the order in which the + release points will be signaled. Of particular concern is that, if the + later of the two release points is signaled before the earlier one, it + may appear to the client as though the Pixmap with the earlier release + point has been released before the server has finished its access to + it. Therefore, in general, clients are strongly advised to avoid using + the same release timeline with different Pixmaps. + + If the server does not support PresentCapabilitySyncobj, a Value error + is generated. + + If either 'acquire-syncobj' or 'release-syncobj' are None or do not + refer to previously imported syncobjs, a Value error is generated. + + If 'acquire-point' or 'release-point' is zero, a Value error is + generated. + + If 'acquire-syncobj' is equal to 'release-syncobj' and 'acquire-point' + is greater than or equal to 'release-point', a Value error is + generated. + 7.1 Requests proposed for a later Present extension version @@ -729,6 +809,31 @@ A.2 Protocol Requests 4 SETofPRESENTCAPABILITY capabilities └─── +┌─── + PresentPixmapSynced + 1 CARD8 major opcode + 1 5 Present opcode + 2 22+2n length + 4 Window window + 4 Pixmap pixmap + 4 CARD32 serial + 4 Region valid-area + 4 Region update-area + 2 INT16 x-off + 2 INT16 y-off + 4 CRTC target-crtc + 4 SYNCOBJ acquire-syncobj + 4 SYNCOBJ release-syncobj + 8 CARD64 acquire-point + 8 CARD64 release-point + 4 CARD32 options + 4 unused + 8 CARD64 target-msc + 8 CARD64 divisor + 8 CARD64 remainder + 8n LISTofPresentNotify notifies +└─── + A.3 Protocol Events ┌─── |