Re: Error Active

[Steffen Rose <ro@emtas.de>]

Hello Wolfgang,

> > What is the standard way to get the state change from Error Passive to
> > Error Active?
> 
> Historically we only supported "increasing" state changes
> "active->warning->passive->bus-off". A few recent drivers do
> also support "passive->warning->active" but most don't (yet).

Historically:
What was the correct error handling in state error passive? Did you ignore it 
in the application? My concrete question is, how did you "define" an error free 
system after this state change in earlier time?

 
> > This will work with the Systec USB interface, but do not work with Peak,
> > Beagle bone, EMS CPC.
> 
> Some time ago I have posted an RFC for providing "decreasing" state
> changes
> as well including proper bus-off recovery for the SJA1000. If would dig it
> out in case you are interested.

I'm afraid, I do not write / change my supported socketcan drivers. But I'm 
interested to read the RFC.
 
> > I have seen the implementation in the can utils.
> > I know, the libsocketcan implements a different way. But I cannot 
> > extract 
> > the relevant parts.
> > And I think a have to poll the current state with it and I search an 
> > event 
> > based mechanism.
> 
> It's not a matter of libsocketcan or ip/iproute2.

I have seen a difference of the can state between
candump -e can0,0~0,#FFFFFFFF
(increase errors - last was error passive)

and
ip -det -stat link show can0
(show error warning state)

This difference was during transmission on an open can bus with Ack error and 
state error passive.
ip got the correct state error passive after receiving a message later, as I 
did check the error active state change.

Do socketcan have different ways to get the current state? Is it a low level 
driver part to read and hold the current state?

(I'm sorry. I'm unsure about the driver I tested in this situation. I think, 
it was the EMS CPC driver and kernel 3.2.0-60-generic. )

-- 
Mit freundlichen Grüßen / Regards
Steffen Rose
www.emtas.de