[Xenomai] RaspberryPi kernel 3.8 issue

Gilles Chanteperdrix gilles.chanteperdrix at xenomai.org
Sun Mar 2 20:04:26 CET 2014


On 03/02/2014 07:57 PM, Gilles Chanteperdrix wrote:
> On 03/02/2014 07:54 PM, Gregory Dymarek wrote:
>> This works!!
>>
>> I thought xenomai does not deal with fiq. Why is it required to enable them
>> in the driver when having xenomai on?
> 
> Because without CONFIG_IPIPE local_irq_restore deals with FIQs
> With CONFIG_IPIPE local_irq_restore does not deal with FIQs
> 
> We can of course rework local_irq_restore to take into account FIQs with
> CONFIG_IPIPE, but that would make local_irq_restore heavier in a lot of
> places, whereas there are in fact only three spots to fix, for only one SOC.
> 
> 
BTW, using FIQs for USB means that USB activity will be able to
influence xenomai latencies. So, it is really not recommended, if there
is a configuration option for disabling the use of FIQ with this driver,
this should be recommended for use with xenomai.

-- 
                                                                Gilles.




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