Hi,
What is the current conscensus for how should PresentOptionAsync work ?
If I remember correctly, the semantic used to be:
. if we present at the current or past msc with the flag, two options:
-> if the ddx doesn't support async swap, we do copy to the screen
pixmap right away
-> if the ddx does support it, we do an async swap right away
. if we present at another msc, things behave as without
PresentOptionAsync, that is we schedule a swap,
and ask at msc-1 to the ddx to swap for msc.
With "Fix use of vsynced pageflips", I get the impression it shifted to:
. Async requested, but driver not having the async option -> do screen
copy (no flips, whatever the msc)
. if Async not requested and flip planned, present at msc-1, else at
msc. (so for flips and Async flag, we do always plan to flip at msc ?
That means always tear, right ?)
That doesn't make a lot of sense to me, can someone clarify ?
I'm afraid this patch could be a workaround to currently broken
behaviour, and not the correct fix.
I CCed Mario Kleiner.
Yours,
Axel Davy
On 29/10/2015 03:53, Michel Dänzer wrote:
On 28.10.2015 19:39, Jammy Zhou wrote:
It is according to the protocol:
"If 'options' contains PresentOptionAsync, and the 'target-msc'
is less than or equal to the current msc for 'window', then
the operation will be performed as soon as possible, not
necessarily waiting for the next vertical blank interval."
Signed-off-by: Jammy Zhou <[email protected]>
---
present/present.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/present/present.c b/present/present.c
index beb4ff0..5900c22 100644
--- a/present/present.c
+++ b/present/present.c
@@ -871,7 +871,7 @@ present_pixmap(WindowPtr window,
xorg_list_add(&vblank->event_queue, &present_exec_queue);
vblank->queued = TRUE;
- if ((pixmap && target_msc >= crtc_msc) || (!pixmap && target_msc >
crtc_msc)) {
+ if (target_msc > crtc_msc) {
ret = present_queue_vblank(screen, target_crtc, vblank->event_id,
target_msc);
if (ret == Success)
return Success;
Looks good to me, but Cc'ing Axel Davy, who made the last change to this
code.
Reviewed-by: Michel Dänzer <[email protected]>
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