On 04/24/2012 11:41 AM, Gilles Chanteperdrix wrote:
> On 04/24/2012 11:31 AM, Michael Trimarchi wrote:
>> Hi
>>
>> On 04/24/2012 10:53 AM, Gilles Chanteperdrix wrote:
>>> On 04/24/2012 10:32 AM, Michael Trimarchi wrote:
>>>> On 04/24/2012 10:13 AM, Gilles Chanteperdrix wrote:
>>>>> On 04/24/2012 10:09 AM, Michael Trimarchi wrote:
>>>>>> This patch includes:
>>>>>>
>>>>>> * Fix invalid virtual address base of MX1_2_TCM * Fix the
>>>>>> minimum delay below which the hardware timer can not be
>>>>>> reprogrammed. The value is the same of that one that is used
>>>>>> to calculate the min_delta_ns
>>>>>>
>>>>>> arch/arm/plat-mxc/time.c 414: clockevent_mxc.min_delta_ns =
>>>>>> clockevent_delta2ns(0xff, &clockevent_mxc);
>>>>>
>>>>> I do not think we can use this value, it is way to high for
>>>>> xenomai needs. In latest releases we use 2us instead of 1us,
>>>>> and according to what a user posted recently, this should be
>>>>> enough, could you test with 2us? And 2us is already what we
>>>>> have in the 3.2 repository.
>>>>>
>>>> As I understood the min delays is in tick and not depend on the
>>>> clock rate.
>>>>
>>>> This is from atmel at91_ipipe_time
>>>>
>>>> min_delta_ticks = ((unsigned long long) clkevt.min_delta_ns *
>>>> clkevt.mult) >> clkevt.shift;
>>>>
>>>> this is exaclty the reverse calculation of
>>>> clockevent_mxc.min_delta_ns
>>>>
>>>> I have already the result in the previous calculation: 0xff is
>>>> the minimun in ticks
>>>
>>> 0xff is too large, it corresponds to 30us on some platforms, could
>>> you please try with 2us? The delay is given as a count of ticks or
>>> as a duration in ns depending on the architecture, it does not
>>> really matter.
>>>
>>
>> Ok, with 0x85 is working (2 uS). I don't find in the documentation
>> the min_delta_ns for this architecture. I will rebase the patch on
>> core-3.2
>
> This is not really a specified constant, finding this minimum value is
> more of a hit and miss. Anyway, on core 3.2, the timers have been
> substantially reworked, and we are able to reuse the clockevent callback
> which has a safety mechanism in addition to the minimum value to avoid
> loosing ticks (in short, the timer is re-read after programming it, and
> if the delay has already passed, the callback returns a negative value,
> which the timer subsystem uses to trigger the irq).
>
> Core-3.2 is not yet supported on ARM for xenomai 2.6. I will do the
> changes and keep you informed.
>
Ok, I have just pushed the changes to the 2.6 branch repository to
support I-pipe core on ARM.
So, the repository for xenomai is:
git://git.xenomai.org/xenoami-2.6.git branch master
and the repository for the core-3.2 ipipe series is:
git://git.denx.de/ipipe.git branch core-3.2
--
Gilles.
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