Synchronization with CRT refresh

[Jim Gettys]

On Tue, 2005-05-03 at 14:32 -0400, Michel Dänzer wrote:
> 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.

Sorry; I guess we all got distracted having to get into the release
business.

It would be good to publish the interface: we need to get the same
interface implemented in other drivers than the DRM as well.
				- Jim

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