[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.


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