Re: Bus off

[Wolfgang Grandegger <wg@grandegger.com>]

On 06/28/2014 03:29 AM, Austin Schuh wrote:
> Thanks everyone!  Reading this thread has been very informative.  I
> was hoping that the buffers would get flushed on BUS_OFF, but it
> sounds like that is hard to do.
> 
> I'm not sure exactly what is going on with the machine in question,
> and I don't really have physical access to sort it out.  The kernel
> messages that I was getting now make a lot more sense.  I'll see if I
> can change how I detect other nodes shutting down to fix that.

You are welcome to show the kernel messages. After re-reading your first
mail of this thread I'm still puzzled what's going on. A node goes
bus-off in case of serious electrical problems on the bus, e.g. improper
termination, bitrate does not matches, etc. It does *not* go bus off
just because no other nodes are on the bus (ack slot error).

Wolfgang.

> On Fri, Jun 27, 2014 at 10:34 AM, Oliver Hartkopp
> <socketcan@hartkopp.net> wrote:
>> On 27.06.2014 18:28, Wolfgang Grandegger wrote:
>>> On 06/27/2014 05:45 PM, Jason R1 White wrote:
>>>> So is it still the recommendation to close the interface to flush the
>>>> queues?
>>>
>>> As I said: the purpose of "restart" is not to do a fast if down->up.
>>>
>>>> Is there anything planned for an ip command or IOCTL to do this?
>>>
>>> It's on the wish list, let's say. Somebody needs to implement it. It's
>>> also not straight-forward because there might be more than one socket
>>> sending out CAN messages. For standard network devices there is no way
>>> to flush all TX queues, IIRC.
>>
>> Probably shutting down the netdevice at BUS_OFF would be an alternative to
>> restart-ms. When the netdevice is down all sockets are notified by -ENETDOWN.
>>
>> We would need some kind of notification when frames got lost anyway. And after
>> -ENETDOWN the application can recover and set up it's communication again.
>>
>> Regards,
>> Oliver
>>
>>
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