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

[Wolfgang Grandegger <wg@grandegger.com>]

On 02/03/2012 04:54 PM, Nikhil Kamath wrote:
> Thanks a lot. I will test by applying the patch .

For a quick try, you can also use (instead of "bitrate 1000000"):

  tq 90 prop-seg 3 phase-seg1 4 phase-seg2 3 sjw 4

Wolfgang.

> Regards,
> Nikhil
> ________________________________
> From: Oliver Hartkopp
> Sent: 03-02-2012 PM 09:19
> To: Wolfgang Grandegger; Nikhil Kamath
> Cc: Linux-CAN
> Subject: Re: [Socketcan-users] CAN Data Transfer not happening at 1Mbps
> 
> 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
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