Re: device driver for the SGI system clock, mmtimer

[Robert Picco]

Bjorn Helgaas wrote:

> On Thursday 16 September 2004 10:32 am, Christoph Lameter wrote:
>  
>
> > On Thu, 16 Sep 2004, Bjorn Helgaas wrote:
> >    
> >
> > > Christoph Lameter wrote:
> > >      
> > >
> > > > The timer hardware was designed around the multimedia timer specification by Intel
> > > > but to my knowledge only SGI has implemented that standard. The driver was written
> > > > by Jesse Barnes.
> > > >        
> > > As far as I can see, drivers/char/hpet.c talks to the same hardware.
> > > HP sx1000 machines (and probably others) also implement the HPET.
> > >      
> > The Intel Multimedia Standard is a earlier and different timer spec.
> >    
>
> I have a spec that's labelled "IA-PC Multimedia Timers", preliminary
> draft of June 2000, revision 0.97, which looks like the one mentioned
> in your patch.
>
> I also have something labelled "IA-PC HPET (High Precision Event
> Timers) Specification", draft of February 2002, revision 0.98,
> which is what drivers/char/hpet.c supports.
>
> I admit I haven't compared them in great detail, but they certainly
> *look* like they're close enough that the same driver could support
> both, and the 0.98 revision history only mentions fairly cosmetic
> changes (like the name :)).
>
> Is there something specific that drivers/char/hpet.c expects that
> your hardware doesn't implement?
>
>  
Look at HPET revision history.  Specifically 0.98 01/20/2002
   * Product name changed: from Multimedia Timer to HPET (High 
Precision Event Timer)

Bob
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