Re: [Socketcan-users] CAN Data Transfer not happening at 1Mbps

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 03.02.2012 09:07, Wolfgang Grandegger wrote:

> On 02/03/2012 05:11 AM, Nikhil Kamath wrote:
>> Hi Wolfgang,
>> Below are the details you asked for:
>>
>> -This means you are not using a mainline kernel, right? Are you using Freescale's ltib linux-2.6.35 tree?
>> Yes , I am not using a mainline kernel , it's from the Freescale's LTIB tree.
>>
>>
>> - From what kernel version is the Flexcan driver derived?
>> I integrated the FlexCAN driver present in linux-2.6.38 mainline Kernel. I am not using the FlexCAN driver given by Freescale since it had issues , for e.g. I used to get the following error -RTNETLINK answers: Operation not supported.

(..)

>> Further , this is the log I got when I executed the following command -
>> root@freescale ~$ ip link set can0 up type can bitrate 1000000
>> flexcan flexcan.0: bitrate error 0.7%
> 
> That might make the trouble. The built-in algorithm to determine the
> bit-timing parameters does not work well for your clock frequency. Try
> to add "sjw=4" to the ip command.


Hi Wolfgang,

to set the sjw value with the ip tool is not implemented in
linux/drivers/net/can/dev.c in 2.6.38 nor in 2.6.35 ...

Maybe Nikhil can update all the stuff in linux/drivers/net/can from the
latest 3.2 kernel.

Alternatively the sjw setting support can be added to older versions by
applying this patch:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=2e1143742789463c00ed5e7f9bf471f2b707b493

Regards,
Oliver