Re: [Xenomai-core] No hardware interrupts with xenomai on ppc405

[Wolfgang Grandegger <wg@domain.hid>]

Philippe Gerum wrote:
> On Mon, 2006-09-11 at 16:22 +0200, Jan Kiszka wrote:
>> Philippe Gerum wrote:
>>> On Mon, 2006-09-11 at 14:20 +0200, Wolfgang Grandegger wrote:
>>>> Matthias Fuchs wrote:
>>>>> Hello Philippe,
>>>>>
>>>>> that helps. I will do some further testing.
>>>>>
>>>>> Matthias
>>>>>
>>>>>
>>>>> On Monday 11 September 2006 12:20, Philippe Gerum wrote:
>>>>>> It's likely an Adeos issue. Could you try this patch? TIA,
>>>>>>
>>>>>> --- arch/ppc/syslib/ppc4xx_pic.c~	2005-10-28 02:02:08.000000000 +0200
>>>>>> +++ arch/ppc/syslib/ppc4xx_pic.c	2006-09-11 12:18:14.000000000 +0200
>>>>>> @@ -72,7 +72,8 @@
>>>>>>  		mtdcr(DCRN_UIC_SR(UIC##n), mask);			\
>>>>>>  		ACK_UIC##n##_PARENT					\
>>>>>>  	}								\
>>>>>> -	if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {		\
>>>>>> +	if (!ipipe_root_domain_p ||					\
>>>>>> +	    !(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {		\
>>>>>>  		ppc_cached_irq_mask[n] |= mask;				\
>>>>>>  		mtdcr(DCRN_UIC_ER(UIC##n), ppc_cached_irq_mask[n]);	\
>>>>>>  	}								\
>>>> Philippe, could you please explain the problem in more detail? And what 
>>>> are the consequences for other PowerPC ARCs and PICs, also for Linux 2.4?
>>> The issue lies in the fact that PICs *_end() routines may be called over
>>> the Xenomai domain, and actually are, most of the time, since
>>> xnintr_irq_handler() -which invokes xnarch_end_irq()- is always called
>>> from the the Xenomai stage in the Adeos pipeline.
>>>
>>> In such a case, we must not check for the Linux-defined IRQ bits (e.g.
>>> IRQ_INPROGRESS), and always send the eoi, since those bits are not
>>> relevant to the Xenomai context. The patch above ensures this.
>>>
>>> And yes, the 2.4 patch has the very same problem, which should be fixed
>>> the same way for all supported ppc platforms in the various PIC
>>> management code. Oops.
>> And why didn't this render PPC-over-2.4 useless, i.e. what is special
>> about this 405-scenario?
>>
> 
> A possible explanation is that configurations only using the timer IRQ
> are not affected, since the decrementer is not subject to this issue
> (the tick handler returns XN_ISR_NOENABLE anyway).

I run RT-Socket-CAN on a CAN PCI Card on my MPC5200 without any 
problems, so far (under Linux 2.4). Here the end function of the PIC:

   static void
   mpc5xxx_ic_end(unsigned int irq)
   {
         if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
                 mpc5xxx_ic_enable(irq);
   }

Matthias, have you printed out the value of status? I'm just curious.

Wolfgang.