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List:       freedesktop-xorg
Subject:    Re: documentation on intel driver behavior?
From:       Jesse Barnes <jbarnes () virtuousgeek ! org>
Date:       2008-02-29 18:18:59
Message-ID: 200802291019.00094.jbarnes () virtuousgeek ! org
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On Friday, February 29, 2008 12:59 am Michel Dänzer wrote:
> On Wed, 2008-02-27 at 16:55 -0800, Eric Anholt wrote:
> > For vblank syncing, we wait for vblank before emitting that copy. 
> > Note that we're not doing anything about guaranteeing that that
> > copy happens in any set amount of time.  We just assume that the
> > hardware will get to it fast enough (and that we were woken up to
> > do this soon enough) that no tearing occurs.
>
> Nice writeup Eric, I'd just like to add that with drm Git, the 3D
> driver can also schedule buffer swaps to be executed by the DRM at an
> arbitrary vertical blank period. This mechanism uses a tasklet to
> mostly eliminate tearing even with several contexts running
> concurrently.

Yeah, the tasklet stuff is really nice.  I wonder if it's something that 
could be made into mostly generic code (ala vblank rework) so that 
other drivers could use it?  I guess that would mean a generic drm 
ioctl for it along with a chunk of generic code for handling the 
tasklets; I'm not sure how much code it would save on the driver side, 
but if it's significant the effort of porting it to the core may be 
worth it.

Jesse
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