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    SubjectRe: [PATCH 2/3] can: add support for Janz VMOD-ICAN3 Intelligent CAN module
    On Fri, Mar 19, 2010 at 09:13:37PM +0100, Wolfgang Grandegger wrote:
    > Ira W. Snyder wrote:
    > > On Fri, Mar 19, 2010 at 04:45:09PM +0100, Wolfgang Grandegger wrote:
    > >> Ira W. Snyder wrote:
    > >>> On Fri, Mar 19, 2010 at 10:01:14AM +0100, Wolfgang Grandegger wrote:
    > >>>> Hi Ira,
    > >>>>
    > >>>> we already discussed this patch on the SocketCAN mailing list and there
    > >>>> are just a few minor issues and the request to add support for the new
    > >>>> "berr-reporting" option, if feasible. See:
    > >>>>
    > >>>> commit 52c793f24054f5dc30d228e37e0e19cc8313f086
    > >>>> Author: Wolfgang Grandegger <>
    > >>>> Date: Mon Feb 22 22:21:17 2010 +0000
    > >>>>
    > >>>> can: netlink support for bus-error reporting and counters
    > >>>>
    > >>>> This patch makes the bus-error reporting configurable and allows to
    > >>>> retrieve the CAN TX and RX bus error counters via netlink interface.
    > >>>> I have added support for the SJA1000. The TX and RX bus error counters
    > >>>> are also copied to the data fields 6..7 of error messages when state
    > >>>> changes are reported.
    > >>>>
    > >>>> Should not be a big deal.
    > >>>>
    > >>> I think this patch came along since my last post of the driver. I must
    > >>> have missed it. I'll try and add support.
    > >> No problem, it's really new. Just just need to enable BEI depending on
    > >>
    > >
    > > I have one final question about this.
    > >
    > > The documentation for the firmware isn't very specific here. I believe
    > > that in order to get any kind of error messages, I need the bus error
    > > feature turned on. What is the expected behavior of an SJA1000 with the
    > > BEI (bus error interrupt) turned off? Will you still get warning
    > > messages for ERROR_ACTIVE -> ERROR_PASSIVE state transitions?
    > Yes. State transitions are enabled with EI and EPI.

    I cannot set the registers directly, but I think I got it right. See

    > > I'm not sure how I would go about testing this feature, either. Ideas?
    > Send messages without cable connected and watch the error messages with
    > "candump any,0:0,#ffffffff". With "ip ... berr-reporting on" you should
    > see additional bus-errors.

    Ok, I tried this. On one controller, I turned on bus-error reporting. On
    the other, I turn off bus-error reporting. I then tried sending lots of
    messages with the cable unplugged. Here is what happened:

    bus-error reporting on:
    Lots of CAN_ERR_BUSERR messages are flooded in candump. There is also a
    CAN_ERR_CRTL_TX_WARNING message, when there are too many TX errors.

    bus-error reporting off:
    There was only one message reported before the controller went into
    ERROR-WARNING state. It was the same CAN_ERR_CRTL_TX_WARNING message as
    above. There was no flooding of CAN_ERR_BUSERR messages.

    Does this seem right? It seems pretty good to me.

    > > I also noticed that I can enable "self test mode" and "listen only mode"
    > > using the same firmware command. It appears that there are netlink
    > > messages for this as well. Should I try and support these, too? I don't
    > > really have any use for them (yet). I assume "self test mode" is
    > > equivalent to "loopback mode" in the netlink messages.
    > List-only is straight forward while "self test mode" is not exactly like
    > "loopback mode", IIRC. Feel free to send a follow-up patch when you have
    > time for a thorough implementation and testing. It's also on my to-do
    > list for the SJA1000.

    Ok, then I'll put this off for a while. Feel free to pester me about it
    when there is a working implementation in the SJA1000 driver for me to
    borrow from. :)

    Thanks for all the help.

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      Last update: 2010-03-19 22:55    [W:0.027 / U:17.400 seconds]
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