Gilles Chanteperdrix wrote:
> Philippe Gerum wrote:
> > Gilles Chanteperdrix wrote:
> > > Hi,
> > >
> > > I would like to implement the (I-pipe) AT91 timer management as
> > > clocksource/clockevent, however, I have a question, how does one choose
> > > the "shift" value in struct clocksource and struct clock_event_device ?
> > >
> > http://ixlabs.cs.pub.ro/category/projects/linux-kernel-library/
> Looks like the thing is working. A concern though: the hardware timer
> used on AT91 wraps fast, so if we want the tsc to work correctly, the
> timer needs to tick every 20ms (which makes using the clock events
> framework pretty useless, but it is mostly useful for other reasons: it
> allows me to test Xenomai on ARM in the clock events case). I have set
> the clock event max_delta_ns member to these 20ms, however when
> inserting the nucleus module, the max_delta_ns member is set to
> ULONG_MAX, so my question is: will the nucleus take care of ticking
> every 20ms ?
Ok. This is now how max_delta_ns is supposed to be used anyway: enabling
NO_HZ breaks the tsc, even if max_delta_ns is not set to ULONG_MAX.
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