Sebastian Smolorz wrote:
> Gilles Chanteperdrix wrote:
>
>>Sebastian Smolorz wrote:
>>
>>>Hi,
>>>
>>>here's a proposal for a minor change in the I-pipe implementation for
>>>ARM. Since it is required for my S3C24xx patch not to call
>>>__ipipe_mach_set_dec directly when the timer is released by the Xenomai
>>>domain I suggest the following changes. The patch comprises the necessary
>>>modifications for PXA, SA1100 and Integrator, too.
>>>
>>>Comments or objections?
>>
>>Why can not you call __ipipe_mach_set_dec directly when the timer is
>>released ?
>
>
> The timer used for generating interrupts operates in auto-reloading mode when
> it is under Linux control. But when Xenomai reloads the timer the mode of
> operation is one-shot (auto-reload feature in hardware is off). So I have to
> make a distinction between setting the dec value by Xenomai for programming
> the next period and setting the dec value to __ipipe_mach_ticks_per_jiffy
> when the timer control is given back to Linux.
>
> The reason for this is the fact that programming a timer on the S3C24xx can
> take some ticks which means that these ticks aren't count whereas time is
> going on in the real world. So it is more reasonable to let the timer reload
> itself when Xenomai hasn't started it. Setting __ipipe_mach_ticks_per_jiffy
> in the Linux interrupt handler would make every period last some ticks
> longer.
You can avoid this problem by adding LATCH or
__ipipe_mach_ticks_per_jiffy to the current value of the match register
in the timer interrupt, as it is done for the SA and PXA architectures.
--
Gilles Chanteperdrix
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