On 05/10/2012 07:29 PM, aubin.rebil...@free.fr wrote:
>> Also, from the sources I could gather (snakeos-sdk), the hardware
>> timer
>> for str8100 is programmed in periodic, auto-reload mode. Obviously,
>> when
>> CONFIG_IPIPE is on, you have to change this to make the timer run in
>> one-shot mode, as required by Xenomai.
>
> I did not know that it was required, i thought it was handy not to reprogram
> the timer each time.
That is likely your problem. You can not assume that a decreasing
counter is all of a sudden a free-running counter with match register.
You have to find the processor datasheet and look at how its registers
must be programmed to run in one-shot mode, if at all possible.
Note that since linux 2.6.24, linux itself switched to one-shot mode,
because it allows high resolution software timers.
>>> #ifdef CONFIG_IPIPE
>>> void __ipipe_mach_demux_irq(unsigned irq, struct pt_regs *regs)
>>> {
>>> // No cascaded interrupt using the VIC
>>> }
>>> #endif /* CONFIG_IPIPE */
>>
>> You probably do not need to define this function if you #define
>> ipipe_mach_irq_mux_p to always be 0.
>>
>
> I do, to avoid an undefined reference.
If you #define ipipe_mach_irq_mux_p(irq) 0
The compilers optimizes away the function call, and there is no
undefined reference. At least with current compilers.
>
> Nevertheless, thank you very much for all this.
>
> When i developped the IPIPE code for this board i followed the
> HOWTO but it's quite vague so I mostly read what has been done
> with other boards and what has been done with linux for this board
> to implement it.
This HOWTO assumes that you understand what you are doing. No HOWTO
guide is a substitute for that unfortunately.
> Therefore, I'm clearly not aware of the interactions between Linux
> and Xenomai. I will definitely read the publications available on
> the Xenomai website.
Well, it is not all that complicated. When xenomai wants to program the
timer it calls ipipe_mach_set_dec, and when a timer interrupt happens,
ipipe_mach_acktimer is called, whether the timer is handled by Linux, or
it has been taken over by Xenomai.
--
Gilles.
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