[Libva] Disabling sync on vblank

[Yann Dirson]

Hello,

When I'm decoding a video (using i965-va-driver, libva 1.7.0) and
displaying frames using
vaPutSurface, it looks as if the latter was syncing on vblank: i
observe the frame rate of my
program to be exactly that of the video mode refresh.

I would like to test if we can do triple-buffering rather than sync on
vblank, and see the
influence on the result.

It does not look like any parameter honored by other software pieces
(Option VSync of the X intel
driver, XV_SYNC_TO_VBLANK, glx's vblank_mode) has any influence.
I cannot find any explicit reference to vsync or vblank in the libva
or va-driver source code,
and at first read (followed Broadwell path, admitedly quickly) it is
not obvious that the
intel-vaapi-driver exlicitly requires any synchro.  Can anyone shed some light ?

Best regards,
-- 
Yann