vblank timestamps and page flipping in DRI2

Saulius Krasuckas saulius2 at ar.fi.lt
Sun Feb 13 11:33:48 CST 2011

There are some news on the $Subject: [1].
(have a look at the chapter "Fine tuned")

I thought it could help Wine fixing such bugs as 6086, 13085, 17260, 22362 

I'll paste the text in just for archiving purposes:

--- quote ---
Fine tuned

The kernel hackers have extended the DRM infrastructure to include 
"precision vblank timestamps", which are explained in detail in the commit 
comment and are relevant to OpenML (Open Media Library) conformity. This 
feature enables the kernel to provide timestamps with an accuracy of a few 
microseconds, allowing applications to detect when the rendering of a new 
image has started ("double-buffer swap"). This can, for instance, be 
relevant for applications where it is important to precisely co-ordinate 
the audio output, or the control of other devices, with the rendering of 
the image. The technology was first implemented for experimental 
psychology and neuroscience applications, but it can also be applied to 
provide (more) jerk-free video playback, animations or desktop effects.

Such timestamps can also be utilised by the new page flipping feature 
available via DRI2. This feature improves the way the kernel synchronises 
the release of an updated image with the moment the graphics hardware 
starts rendering the new image (Vsync). Synchronising the release avoids 
such distortions as flickering, tearing or incomplete rendering, as it 
prevents situations where one half of a displayed image is part of the old 
image while the other half is part of the new image . for instance with 
individual movie frames. In kernel version 38, the graphics driver support 
required for both features will be available via the AMD drivers (1, 2) 
and the Intel drivers (1, 2). The NVIDIA drivers currently only support 
page flipping (1, 2).
--- quote ---


[1] http://www.h-online.com/open/features/Kernel-Log-Coming-in-2-6-38-Part-1-Graphics-1176900.html?artikelseite=1;page=2
[2] http://bugs.winehq.org/show_bug.cgi?id=6086

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