Re: CAN Data Transfer not happening at 1Mbps

Re: CAN Data Transfer not happening at 1Mbps

[Wolfgang Grandegger]

On 02/02/2012 03:24 PM, Nikhil Kamath wrote:
> Hi,
> I am having a i.Mx35 PDK board   running linux-2.6.35 kernel. CAN communication is done using the socket CAN driver  taken from the mainline kernel.

This means you are not using a mainline kernel, right? Are you using
Freescale's ltib linux-2.6.35 tree?

> Issue - Data transfer not happening at 1Mbps bitrate  , works fine on other bitrates.
> 
> Please help in resolving the issue.

- From what kernel version is the Flexcan driver derived?
- What does "dmesg" report when you load the driver?
- What does "ip -d -s link show can0" report after an unsuccessful
  transfer?
- What does "candump -e any,0:0,#FFFFFFFF" report while sending
  messages?

Wolfgang.

PS:

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

[Nikhil Kamath]

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.

- What does "dmesg" report when you load the driver?
flexcan netdevice driver
flexcan flexcan.0: device registered (reg_base=c8978000, irq=43)
flexcan flexcan.0: writing ctrl=0x25292004

-What does "ip -d -s link show can0" report after an unsuccessful
  transfer?
root@freescale ~$ ip -d -s link show can0
2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
    link/can
    can state ERROR-PASSIVE restart-ms 0
    bitrate 1007575 sample-point 0.727
    tq 90 prop-seg 3 phase-seg1 4 phase-seg2 3 sjw 1
    flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
    clock 66500000
    re-started bus-errors arbit-lost error-warn error-pass bus-off
    0          0          0          1          1          0
    RX: bytes  packets  errors  dropped overrun mcast
    19         5        0       0       0       0
    TX: bytes  packets  errors  dropped carrier collsns
    2          0        0       0       0       0


-What does "candump -e any,0:0,#FFFFFFFF" report while sending
  messages?
I received a message saying invalid option for 'e' in the above command, I tried using  'L' option instead to check if something gets logged , but at 1 Mbps logging was not happening.


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%
flexcan flexcan.0: writing ctrl=0x051ae052

Thanks and regards,
Nikhil


-----Original Message-----
From: Wolfgang Grandegger [mailto:wg@grandegger.com]
Sent: Thursday, February 02, 2012 8:20 PM
To: Nikhil Kamath
Cc: socketcan-users@lists.berlios.de; Linux-CAN
Subject: Re: [Socketcan-users] CAN Data Transfer not happening at 1Mbps

On 02/02/2012 03:24 PM, Nikhil Kamath wrote:
> Hi,
> I am having a i.Mx35 PDK board   running linux-2.6.35 kernel. CAN communication is done using the socket CAN driver  taken from the mainline kernel.

This means you are not using a mainline kernel, right? Are you using Freescale's ltib linux-2.6.35 tree?

> Issue - Data transfer not happening at 1Mbps bitrate  , works fine on other bitrates.
>
> Please help in resolving the issue.

- From what kernel version is the Flexcan driver derived?
- What does "dmesg" report when you load the driver?
- What does "ip -d -s link show can0" report after an unsuccessful
  transfer?
- What does "candump -e any,0:0,#FFFFFFFF" report while sending
  messages?

Wolfgang.

PS:

please do not use this mailing list any longer but send your questions to the new "linux-can" mailing list address "linux-can@vger.kernel.org".
For subscription or mailing list archives please have a look to:

   http://vger.kernel.org/vger-lists.html#linux-can

Mail archives of the new linux-can mailing list can be found at:

   http://dir.gmane.org/gmane.linux.can
   http://marc.info/?l=linux-can&r=1&w=2


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

[Wolfgang Grandegger]

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.

OK.

> - What does "dmesg" report when you load the driver?
> flexcan netdevice driver
> flexcan flexcan.0: device registered (reg_base=c8978000, irq=43)
> flexcan flexcan.0: writing ctrl=0x25292004
> 
> -What does "ip -d -s link show can0" report after an unsuccessful
>   transfer?
> root@freescale ~$ ip -d -s link show can0
> 2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
>     link/can
>     can state ERROR-PASSIVE restart-ms 0
>     bitrate 1007575 sample-point 0.727
>     tq 90 prop-seg 3 phase-seg1 4 phase-seg2 3 sjw 1
>     flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1
>     clock 66500000
>     re-started bus-errors arbit-lost error-warn error-pass bus-off
>     0          0          0          1          1          0
>     RX: bytes  packets  errors  dropped overrun mcast
>     19         5        0       0       0       0
>     TX: bytes  packets  errors  dropped carrier collsns
>     2          0        0       0       0       0

The CAN controller has reached the error passive state. It seems that
there are electrical problems on the CAN bus, e.g. improper termination
or bit-timing.

> -What does "candump -e any,0:0,#FFFFFFFF" report while sending
>   messages?
> I received a message saying invalid option for 'e' in the above command, I tried using  'L' option instead to check if something gets logged , but at 1 Mbps logging was not happening.

Your version of candump seems to be quite old. Just try without "-e" but
the statistics above already points to the problem.

> 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.

Wolfgang.

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

[Oliver Hartkopp]

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

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

[Wolfgang Grandegger]

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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