Synchronization with CRT refresh

[Michel Dänzer]

On Tue, 2005-05-03 at 12:35 -0400, Jim Gettys wrote:
> On Tue, 2005-05-03 at 11:58 -0400, Adam Jackson wrote: 
> > On Tuesday 03 May 2005 11:02, Jim Gettys wrote:
> > > Unfortunately, this has never been implemented on Linux.
> > >
> > > Volunteers gratefully accepted...
> > 
> > I looked at doing this for i128 a while ago, and there's a few issues involved 
> > in getting it right.  The simple first one is actually wiring up the sync 
> > counter from the driver, afaict there's no existing driver infrastructure for 
> > this.  Is there any sample implementation of a driver that exports a sync 
> > counter?
> 
> Not commonly available: we did implementations on closed source UNIX in
> the early 1990's. Alan Cox started on a kernel framework for this for
> Linux to plug into just before he went to graduate school; I don't know
> what happened to the code.

Ahem. I implemented this in the DRM years ago. I even extended the
interface to optionally generate a signal instead of blocking in the
ioctl on request by yours truly and Keith Packard, but I'm still not
aware of anything using that. Oh well.


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer