Re: [Xenomai] imx28 rtcan flexcan system freezes

[Alexandre COFFIGNAL <acoffignal@geral.com>]

Le 23/01/2014 13:54, Alexandre COFFIGNAL a écrit :
>
> Le 23/01/2014 12:36, Wolfgang Grandegger a écrit :
>> Hi Gilles,
>>
>>
>>
>> On Thu, 23 Jan 2014 11:04:44 +0100, Gilles Chanteperdrix
>>
>> <gilles.chanteperdrix@xenomai.org> wrote:
>>
>>> On 01/22/2014 03:12 PM, Gilles Chanteperdrix wrote:
>>>> On 01/22/2014 03:04 PM, Alexandre COFFIGNAL wrote:
>>>>> Le 22/01/2014 14:30, Gilles Chanteperdrix a écrit :
>>>>>> On 01/22/2014 02:27 PM, Alexandre COFFIGNAL wrote:
>>>>>>> Le 22/01/2014 13:00, Gilles Chanteperdrix a écrit :
>>>>>>>> On 01/22/2014 12:36 PM, Alexandre COFFIGNAL wrote:
>>>>>>>>>>> + cf->data[3]=((data0 >> 0)  & 0xFF) ;
>>>>>>>>>>> +        cf->data[2]=((data0 >> 8) & 0xFF) ;
>>>>>>>>>>> +        cf->data[1]=((data0 >> 16) & 0xFF) ;
>>>>>>>>>>> +        cf->data[0]=((data0 >> 24) & 0xFF) ;
>>>>>>>>>>> +        cf->data[7]=((data1 >> 0) & 0xFF) ;
>>>>>>>>>>> +        cf->data[6]=((data1 >> 8) & 0xFF) ;
>>>>>>>>>>> +        cf->data[5]=((data1 >> 16) & 0xFF) ;
>>>>>>>>>>> +        cf->data[4]=((data1 >> 24) & 0xFF) ;
>>>>>>>>>>> rtcan flexcan works perfectly.
>>>>>>>>>>> is  anyone know what is the problem with first instructions ?
>>>>>>>>>> Probably mb->data does not have the right alignment. Could you
>> not
>>
>>>>>>>>>> arrange to get it properly aligned? Failing that, you should use
>>>>>>>>>> put_unaligned instead of open coding it.
>>
>>
>> How are unaligned accesses handled on your system? Alexandre,
>>
>> what does "cat /proc/cpu/alignment" report? Aligned access
>>
>> would be better, I agree.
>>
>>
>>
>>>>>>>>> here structures used in flexcan driver, it seem to be aligned
>>>>>>>> I am talking about the alignment of cf->data, since obviously, 
>>>>>>>> that
>>>>>>>> is
>>>>>>>> the one which is causing problems.
>>>>>>> Thank a lot, put_unaligned fix this issue if you want, i can send a
>>>>>>> path
>>>>>> The other solution (getting cf->data to be properly aligned) 
>>>>>> would be
>>>>>> more efficient, why is not it possible to get cf->data properly
>>>>>> aligned?
>>>>> I think, i can't get cf->data to be properly aligned because "cf" is
>>>>> receive internal frame representation within the ring buffer
>>>>> of a struct rtcan_socket and struct rtcan_rb_frame is a generic
>>>>> structure used in all rtcan drivers .
>>>> Well, if you fix rtcan_rb_frame to be aligned, it will be aligned for
>>>> all drivers, so that looks like a worthwile improvement...
>>> Wolfgang, what do you think? Should we change the alignment of
>>> rtcan_rb_frame::data, or use put_unaligned on ARM?
>>
>>
>> I realized the mail and wonder why this problem does not show up with
>>
>> vanilla
>>
>> Linux. Maybe we need to port over some patch from there. I will have a
>>
>> closer
>>
>> look this even or over the weekend.
>>
>>
>>
>> Wolfgang.
>>
>>
>>
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>
> Hi,
>
> "cat /proc/cpu/alignment" report
> User:           0
> System:         0
> Skipped:        0
> Half:           0
> Word:           0
> DWord:          0
> Multi:          0
> User faults:    0 (ignored)
>
> something wrong with that ?
>
> Alexandre.
>
>
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For your information :
Actualy my kernel is linux 3.8.13 vanilla from 
https://www.kernel.org/pub/linux/kernel/v3.x/"
with Adeos/Xenomai Real-time patch 2.6.3 from
download.gna.org/xenomai/stable/xenomai-2.6.3.tar.bz2