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Re: Two timer in FIQ mode


Sorry, I wrote and i misspelled, I want tell this:

I'd like use the FIQ vs IRQ because I don't want the variable time between
CPU 'signal' and the interrupt routine.
I check with the oscilloscope two signals: the CPU (CPU timer2 out toggle)
and a IO (PTF4).
In the FIQ mode, the time between these signal is constant (about 7us)
In the IRQ mode, the time between these signal is variable (from 7us to
150us)
This is a problem for my application. For this reason i choose the FIQ.
Now, Could I remove in the IRQ this variable time? Is it possible?
Thanks,
dS, MS.

>
> You (Andrew and Mark) wrote:
>
> > On Fri, 2004-11-19 at 07:35, Andrew Lunn wrote:
> > > On Fri, Nov 19, 2004 at 11:43:39AM +0100, Sicheri Marco wrote:
> > > > I all,
> > > > I Have the Samsung s3c44b0x.
> > > > I'd like use two timer in interrupt mode.
> > > > So that i use the TIMER2 and the TIMER3 (use the
> cyg_interrupt_create()).
> > > >
> > > > First step: run only the timer2 in fiq mode every 1ms. It works ok
> > > > Second step: run only the timer3 in fiq mode every 2ms. It works ok
> > > > Now: run timer2 in FIQ mode and the timer3 in IRQ mode. They work
ok.
> > > > But: if i run timer2 in FIQ mode and the timer3 in FIQ mode, they
> don't
> > > > work, and the system is lock.
> > >
> > > FIQ is not heavily used so i would not be supprised if there were a
> > > few bugs remaining. Probably its a reentrance problem, ie handling a
> > > second FIQ will still handling the first. Take a look at vectors.S and
> > > see if you can find such a problem.
> > >
> >
> > That is probably the case.
> >
> > It is good to keep in mind that FIQ support in vectors.S simply
> > uses the same handling as a normal IRQ. There is no advantage to
> > using an FIQ vs IRQ. The current code was intended to workaround
> > poorly designed hardware which used the FIQ input for normal
> > interrupts. Proper FIQ support would need to do something else.
> >
> > --Mark
>
> I'd like use the FIQ vs IRQ because I don't want the variable time between
> CPU 'signal' and the interrupt routine.
> I check with the oscilloscope two signals: the CPU (CPU timer2 out toggle)
> and a IO (PTF4).
> In the FIQ mode, the time between these signal is constant (about 7us)
> In the IRQ mode, the time between these signal is variable (from 7us to
> 150us)
> This is a problem for my application. For this reason i choose the IRQ.
> Now, Could I remove in the IRQ this variable time? Is it possible?
> Thanks,
> dS, MS.


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