Sebastian Smolorz wrote:
Sebastian Smolorz wrote:
Hi Jan,
Jan Kiszka wrote:
Wolfgang Grandegger wrote:
you know, on the SJA1000 the bus error interrupt can result in high
error interrupt rates and even hang the system on slow processors. Just
unplugging the CAN cable can cause such interrupt flooding. This
problem
popped up again recently and Sebastian proposed:
Last summer we had a discussion about the BEI issue on the
socketcan-ML. Two additional handling policies popped up:
1. The interface could restart itself after an amount of BEIs, thus
taking responsibility from the user application.
2. The BEI could be completely disabled if no one is interested in
this ype of error frame.
As 2. is also my preferred solution, I have implemented it. The only
downside is that you do not see the error counter increasing when
/proc/rtcan/devices is inspected. We also discussed 1., but
RT-Socket-CAN does not restart the CAN controller by purpose and just
stoppping it requires user intervention.
And if there is someone listening, how is the flooding issue on cable
unplug etc. solved by option 2?
Hm, maybe we could implement 1 additionally (but without automatical
restart)?
A more precise suggestion: What about letting BEIs appear until passive mode
is reached and if the TX error counter doesn't count up any more (indication
of start-up situation discovered by the SJA1000) the driver ceases to read
out ECC any further (thanks Stephane for the hint). The controller would be
still operating but not reporting BEIs any more. There has to be some
mechanism to let BEIs through after the situation has normalized. Maybe the
driver could check inside the interrupt handler if active mode was reached
again after the above situation occured.
Well, this is rather sophisticated and needs some more careful
evaluation. We might also reach the passive level slowly without
flooding. Furthermore, the method should also be applicable for other
controllers.
Let's implement 1. and downscaled printk and wait for the users reaction
, see also my other mail. Then we should bring up this discussion again
on the Socket-CAN-ML to negotiate a common solution.
OK?
Wolfgang.
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