RTEMS - rtems_clock_get_uptime() fails during timer tick

[Rolf Schroedter]

On 25.02.2011 14:27, Joel Sherrill wrote:
> On 02/25/2011 03:06 AM, Rolf Schroedter wrote:
>> Hi Joel,
>> IMO your suggestion to let the nanoseconds handler return a value larger
>> than a tick is the cleanest solution.
>> I implemented it for the LEON3 BSP and it seems to work.
>>
>> Fortunately the LEON3 timer has a InterruptPending(IP) hardware flag
>> which can be polled and manually reset.
>> Therefore two changes were necessary:
>>
>> 1. Install a LEON3 timer interrupt handler resetting the IP flag on
>> every timer tick.
>> 2. Change the LEON3 nanoseconds-handler to check the IP flag:
>>      read nanoseconds from timer register
>>      if ( timer_interrupt_pending )
>>           nanoseconds += timer_tick
>>
>> I'll post the patch to Jiri Gaisler, shall I also post it here ?
>>
> Please.   If you can also hack it into the other sparc BSPs,
> that would be appreciated.
>
> Actually file this as a PR.   This is something I would like
> to apply to appropriate release branches.
>
> --joel

Okay. I'm currently not in my office, so I'll submit the patches next week.
 
As Manuel Coutinho pointed out, his patches for ERC32 & LEON2 are here:
http://www.rtems.com/ml/rtems-users/2009/march/msg00210.html

@Manuel, perhaps we shall collect these patches together with my LEON3
patch into a single PR.

Rolf.

>> Regards, Rolf
>>
>> Joel Sherrill wrote, On 24.02.2011 14:28:
>>> Can the BSP's get nanoseconds handler return a value that is
>>> more than a clock tick?  This case is just on the edge of
>>> wrapping the count down timer.  If the counter goes negative,
>>> does the get nanoseconds since last tick handler in the
>>> BSP "do the right thing"
>>>
>>> On 02/24/2011 01:51 AM, Rolf Schroedter wrote:
>>>> I tried to protect the call to rtems_clock_get_uptime() from
>>>> interrupts
>>>> (this was easier than to recompile RTEMS):
>>>>
>>>> #define _get_uptime( _ptr_uptime )        \
>>>> {                        \
>>>>        rtems_interrupt_level   _level;        \
>>>>                            \
>>>>        rtems_interrupt_disable(_level);        \
>>>>        rtems_clock_get_uptime( _ptr_uptime );    \
>>>>        rtems_interrupt_enable(_level);        \
>>>> }
>>>>
>>>> But surprisingly (at least for me) this didn't solve the problem.
>>>> Okay, I'll try to grab into the RTEMS sources.
>>>>
>>>> Thanks&   regards,
>>>> Rolf.
>>>>
>>>>
>>>> On 24.02.2011 01:23, Gedare Bloom wrote:
>>>>> Hi,
>>>>>
>>>>> I suppose if your code is interrupting the rtems_clock_tick, this
>>>>> behavior might happen. Can you try to add an ISR_Disable / ISR_Enable
>>>>> protection around the call to "_Timestamp_Add_to(&_TOD_Uptime,&tick
>>>>> );" in cpukit/score/src/coretodtickle.c and see if the problem
>>>>> disappears?
>>>>>
>>>>> -Gedare
>>>>>
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>>
>


-- 
------------------------------------
Rolf Schroedter
German Aerospace Center
Institute of Planetary Research
D-12489 Berlin, Rutherfordstrasse 2
Tel/Fax:  (+49) (30) 67055-416/384
Email:    Rolf.Schroedter at dlr.de