Re: [Xenomai-core] Some questions about the ARM port (Integrator vs. PXA)

[Detlef Vollmann <dv@domain.hid>]

Gilles Chanteperdrix wrote:
> You can even do this in __ipipe_mach_set_dec, this avoid the need to
> modify I-ipipe non-machine specific code. Something like:
> 
> void __ipipe_mach_set_dec(unsigned long delay)
> {
>     if (delay < 8)
>         ipipe_trigger_irq(__ipipe_mach_timerint);
>     else
>         OSMR0 = OSCR + delay;
> }

Thanks, ipipe_trigger_irq() is exactly what I was looking for.

I'll just add another test after the update of OSMR0 for the
case that we got interrupted between the comparison and the
assignment.  And in that (probably very rare) case I accept that
I loose a timer tick :-(

Also, this way the timer comes a bit early, so any handler that
checks the TSC might think that this is the wrong interrupt --
and wait forever for the correct one.
But the only other option would be the busy wait...

The question about recursion remains:
If a domain decides in its timer interrupt handler to reprogram
the timer by calling __ipipe_mach_set_dec() (indirectly), and
we already are too close to the next match, then that interrupt
handler is called recursively.
Is every ipipe domain expected to cope with this?

 Detlef Vollmann

-- 
Detlef Vollmann   vollmann engineering gmbh
Linux and C++ for Embedded Systems    http://www.vollmann.ch/
Linux for PXA270 Colibri module: http://www.vollmann.ch/en/colibri/