Re: [PATCH] can: kvaser_usb: Add support for Kvaser CAN/USB devices

On Sun, Aug 05, 2012 at 10:43:55PM +0200, Wolfgang Grandegger wrote:

On 08/02/2012 01:56 PM, Marc Kleine-Budde wrote:

quoted

On 08/02/2012 12:53 PM, Olivier Sobrie wrote:

...

quoted

quoted

I actually implemeted it as you said and here is what I observed in
candump output with restart_ms set to 100 ms:

t0: Short circuit between CAN-H and CAN-L + cansend can1 123#1122
  can1  2000008C  [8] 00 04 90 00 00 00 00 00   ERRORFRAME
	controller-problem{rx-error-warning}
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-error
  can1  2000008C  [8] 00 10 90 00 00 00 00 00   ERRORFRAME
	controller-problem{rx-error-passive}
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-error
  can1  200000C8  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-off
	bus-error
...

FYI, the option "-td" nicely shows the timing. I assume that the
"warning->passive->bus-off" sequence repeats because automatic bus-off
is active via ip option "restart-ms xx ms". What I'm missing is the
message "restarted-after-bus-off". Maybe it's not listed here...

Indeed it's missing. Please look at the patch I just sent if it is now
correct or not.

quoted

quoted

  can1  2000008C  [8] 00 04 90 00 00 00 00 00   ERRORFRAME
	controller-problem{rx-error-warning}
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-error
  can1  2000008C  [8] 00 10 90 00 00 00 00 00   ERRORFRAME
	controller-problem{rx-error-passive}
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-error
  can1  200000C8  [8] 00 00 90 00 00 00 00 00   ERRORFRAME
	protocol-violation{{tx-recessive-bit-error,error-on-tx}{}}
	bus-off
	bus-error

t1: short circuit removed
  can1  123  [2] 11 22
  can1  20000100  [8] 00 00 00 00 00 00 00 00   ERRORFRAME
	restarted-after-bus-of

The echo coming before the restart looks weird? No?

Yes. It should come later.

Ok I've to change this.

quoted

quoted

Shouldn't we drop the frame once BUF-OFF is reached?

No.

Ok.

quoted

No, I don't think so. But wait for Wolfgang, here's more into error
handling then me.

Looking to your code it's not clear to me how you do recovery from
bus-off (called "restart"). This is usually done via
do_set_mode(CAN_MODE_START), either manually (restart-ms==0) or
automatically (restart-ms>0). Could you please explain how the device
does bus-off recovery? Does the hardware do it automatically? This
should be suppressed if if restart-ms==0 (as Marc already pointed out).

The hardware automatically recovers from BUS-OFF if it isn't stopped.
In the second version of the patch I just sent, I put the device off if
restart-ms == 0.

Thanks,

-- 
Olivier