Re: [Socketcan-users] [socketcan]problem to using CAN with BeagleBone Black A5A

[Wolfgang Grandegger <wg@grandegger.com>]

On 06/10/2013 09:54 PM, Michael Luxen wrote:
> Hello Wolfgang,
> 
> from the Raspberry Pi point of view I can say that I've patched already the original raspbmc based kernel MCP251x driver to the MCP2515 asynchronous of Andre B. Oliveira. I've also patched the raspbmc SPI driver to use DMA mode for low latency issues.
> With these modifications the MCP2515 runs on my setup with the Raspi without any message lost. Also with busload >50% @ 1000kbit/s.

Ah, I was not aware of that. What about pushing these modifications to
mainline? We would assist in getting it accepted.

> More details for Raspi users can be found here:
> http://elinux.org/RPi_CANBus
> 
> But keep in mind as soon as a second MCP2515 is used on the MCP2515 one of them stops sending/receiving after a few seconds as the ISR seems to hang.

OK, sounds more like a hardware problem.

Wolfgang.

> Regards
> Mike
> 
> -----Ursprüngliche Nachricht-----
> Von:	Wolfgang Grandegger <wg@grandegger.com>
> Gesendet:	Mo 10.06.2013 19:50
> Betreff:	Re: [Socketcan-users] [socketcan]problem to using CAN with BeagleBone Black A5A
> An:	Michael Luxen <mluxen@gmx.net>; 
> CC:	Oliver Hartkopp <socketcan@hartkopp.net>; linux-can@vger.kernel.org; 
>> On 06/10/2013 06:24 PM, Michael Luxen wrote:
>> ...
>>>>> I'm not sure about the cpu-load, latency and messages lost problems. My 
>>>> experience on the RasperryPi is that 2x MCP2515 on one SPI-Channel doesn't 
>> work 
>>>> with busload above 10% at 500kbit/s.
>>>>
>>>> That's not that much. But it's an interesting information to get an 
>> estimation
>>>> what one might get with this setup.
>>> But keep in mind that the Raspi has only one SPI channel where I've connected 
>> two MCP2515 (only independetn ChipSelect and Interrupt lines). Therefore I'm 
>> interested in to sees how the BeagleBone Black can handle two MCP2515 on 
>> idenpendent SPI channels (SPI1/SPI2).
>>
>> The problem is not (only) SPI hardware but software. The CAN messages
>> are not read-out quickly enough due to latencies resulting in message
>> losses. May user do report that problem with the MPC251x. The following
>> link does have some nice figures:
>>
>>   http://clientes.netvisao.pt/anbadeol/mcp2515.html
>>
>> I think the software can do better but still latency is critical for the
>> MPC251x, especialy MPC2510.
>>
>> Wolfgang.
>>
>>
>>
>>
>>
>>
>>
>>
>>> Regards
>>> Mike
>>>  
>>>>> -----Ursprüngliche Nachricht-----
>>>>> Von:	Oliver Hartkopp <socketcan@hartkopp.net>
>>>>> Gesendet:	Sa 08.06.2013 13:46
>>>>> Betreff:	Re: AW: [Socketcan-users] [socketcan]problem to using CAN with 
>>>> BeagleBone Black A5A
>>>>> An:	Michael Luxen <mluxen@gmx.net>; 
>>>>> CC:	linux-can@vger.kernel.org; 
>>>>>> Hello Mike,
>>>>>>
>>>>>> thanks for pointing to that comprehensive documentation.
>>>>>>
>>>>>> I was asked by a colleague how to get both internal CAN controllers working
>>>>>> instead of adding SPI-based MCP2515 interfaces.
>>>>>>
>>>>>> Good job!
>>>>>>
>>>>>> Best regards,
>>>>>> Oliver
>>>>>>
>>>>>> On 07.06.2013 21:46, Michael Luxen wrote:
>>>>>>> Hello Mohamed,
>>>>>>>
>>>>>>> is you question still open or answered already?
>>>>>>>
>>>>>>> If still open, please have a look on this page where you can find how to 
>>>>>> enable the CAN-Devices on BeagleBone Black.
>>>>>>> http://www.aero-box.co.uk/beaglebone-black#TOC-Enable-CANbus-device
>>>>>>>
>>>>>>> The only thing you have to do is to edit the am335x-bone-common.dtsi file 
>>>> for 
>>>>>> enabling dcan0 and/or dcan1.
>>>>>>> Please have in mind that dcan0 is normaly used for the optional Capes, as 
>>>>>> they use the I2C2 pins which are muxed on the same pins than dcan0.
>>>>>>> Nevertheless I've edited am335x-bone-common.dtsi successfully to enable 
>>>> dcan0 
>>>>>> and dcan1. On my BeagleBone Black (Hardware A5A) eveything is running fine 
>>>> on 
>>>>>> both internal CAN-Interfaces with latest Angstrom and latest Debian as 
>> well.
>>>>>>> Keep in mind that you have to put a CAN-transceiver on the Pins 20/19 
>>>> (DCAN0) 
>>>>>> an 24/26 (DCAN1) on your BeagleBone Black.
>>>>>>>
>>>>>>> Regards
>>>>>>> Mike
>>>>>>>
>>>>>>> -----Ursprüngliche Nachricht-----
>>>>>>> Von:	Martin Gysel <m.gysel@gmail.com>
>>>>>>> Gesendet:	Di 04.06.2013 13:32
>>>>>>> Betreff:	Re: [Socketcan-users] [socketcan]problem to using CAN with 
>>>>>> BeagleBone Black A5A
>>>>>>> An:	linux-can@vger.kernel.org; 
>>>>>>> CC:	socketcan-users@lists.berlios.de; 
>>>>>>>> Am 25.05.2013 00:49, schrieb Mohamed HAMZAOUI:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I started with beaglebone black A5A, i installed on it the latest
>>>>>>>>> Angstrom image with : Linux beaglebone 3.8.13 #1 SMP Mon May 20
>>>>>>>>> 17:07:58 CEST 2013 armv7l GNU/Linux
>>>>>>>>>
>>>>>>>>> I have a problem when I try to add a can device, i load with modprobe
>>>>>>>>> all necessary kernel module (can, ti_hecc, c_can, c_can_platform,
>>>>>>>>> can-raw, can-bcm) but when i execute
>>>>>>>>>> ip link add can0 type can
>>>>>>>>> I have : RTNETLINK answers: Operation not supported
>>>>>>>>> I used a recent version of iproute2.
>>>>>>>>
>>>>>>>> did you initialize the can module? do you use a can cape? if yes, does
>>>>>>>> your kernel already include the needed dts to enable the can module?
>>>>>>>>
>>>>>>>> /martin
>>>>>>>>
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