From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Date: Mon, 3 Jul 2006 15:00:44 +0200
Subject: Re: [Xenomai-core] Some questions about the ARM port (Integrator
	vs.	PXA)
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To: Detlef Vollmann <dv@domain.hid>, Jan Kiszka <jan.kiszka@domain.hid>, xenomai@xenomai.org

Gilles Chanteperdrix wrote:
 > Detlef Vollmann wrote:
 >  > It's not so difficult to work around the problem for a single system.
 >  > What's difficult is to find a solution in a framework that wasn't
 >  > built with such a problem in mind.
 > 
 > Actually, all architectures have a delay below which they can not be
 > reprogrammed fast enough. This delay is simply 0 for all of them.
 > 
 > How about rewriting rthal_timer_program_shot as:
 > 
 > static inline void rthal_timer_program_shot (unsigned long delay)
 > {
 >     if(delay < __ipipe_mach_min_delay)
 >         rthal_trigger_irq(RTHAL_TIMER_IRQ);
 >     else
 >         __ipipe_mach_set_dec(delay);
 > }
 > 
 > And define __ipipe_mach_min_delay to be 8 ticks for the PXA architecture ?

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;
}

Supposing that OSSR=OSSR_M0 is done elsewhere.

-- 


					    Gilles Chanteperdrix.