[Xenomai-core] rt_intr_enable() requierd after rt_intr_create

[Xenomai-core] rt_intr_enable() requierd after rt_intr_create

[Ignacio García Pérez]

Hi,

I noticed that when an interrupt object is created using
rt_intr_create(), it is created disabled, and a call to rt_intr_enable()
is necessary for the ISR to be called.

Question is: is this the expected behaviour?. If so, I think this should
be mentioned somewhere in the rt_intr_create documentation. In fact,
from reading the docs one could infer the opposite.

On a related issue, I noticed that the rt_intr_enable() documentation says:

"Enables the hardware interrupt line associated with an interrupt
object. Over Adeos-based systems which mask and acknowledge IRQs upon
receipt, this operation is necessary to revalidate the interrupt channel
so that more interrupts from the same source can be notified."

Is this correct?. I ask because the rt_intr_create() documentation tells
you to just return RT_INTR_ENABLE from the ISR if you want this. It's
confusing.


Nacho.

Re: [Xenomai-core] rt_intr_enable() requierd after rt_intr_create

[Philippe Gerum]

Ignacio García Pérez wrote:
> Hi,
> 
> I noticed that when an interrupt object is created using
> rt_intr_create(), it is created disabled, and a call to rt_intr_enable()
> is necessary for the ISR to be called.
> 
> Question is: is this the expected behaviour?.

Yes. You don't necessarily want to take interrupts immediately after the 
object is created, for which you might have some additional housekeeping 
chores to perform before that.

  If so, I think this should
> be mentioned somewhere in the rt_intr_create documentation. In fact,
> from reading the docs one could infer the opposite.
> 

Ok, will add a note to rt_int_create().

> On a related issue, I noticed that the rt_intr_enable() documentation says:
> 
> "Enables the hardware interrupt line associated with an interrupt
> object. Over Adeos-based systems which mask and acknowledge IRQs upon
> receipt, this operation is necessary to revalidate the interrupt channel
> so that more interrupts from the same source can be notified."
> 
> Is this correct?. I ask because the rt_intr_create() documentation tells
> you to just return RT_INTR_ENABLE from the ISR if you want this. It's
> confusing.
> 

Well, the text seems pretty clear to me here: rt_intr_enable() specifies 
that the re-enabling _operation_ should be carried on after IRQ receipt, 
but not necessarily using rt_intr_enable(). Returning RT_INTR_ENABLE 
from the ISR is just the other way to do this.

> 
> Nacho.
> 
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-- 

Philippe.