Re: [PATCH v5 2/5] can: kvaser_usb: Consolidate and unify state change handling

Wolfgang Grandegger
2015-01-21T16:13:56Z

On Wed, 21 Jan 2015 10:36:47 -0500, "Ahmed S. Darwish"
<darwish.07@gmail.com> wrote:
> On Wed, Jan 21, 2015 at 03:00:15PM +0000, Andri Yngvason wrote:
>> Quoting Ahmed S. Darwish (2015-01-21 14:43:23)
>> > Hi!
>
> ...
>
>> > <-- Unplug the cable -->
>> >
>> > (000.009106) can0 20000080 [8] 00 00 00 00 00 00 08 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{8}{0}}
>> > (000.001872) can0 20000080 [8] 00 00 00 00 00 00 10 00

For a bus-errors I would also expcect some more information in the
data[2..3] fields. But these are always zero.

>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{16}{0}}
>> [...]
>> > error-counter-tx-rx{{80}{0}}
>> > (000.001910) can0 20000080 [8] 00 00 00 00 00 00 58 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{88}{0}}
>> > (000.001753) can0 20000084 [8] 00 08 00 00 00 00 60 00
>> > ERRORFRAME
>> > controller-problem{tx-error-warning}
>> Good.
>> > bus-error
>> > error-counter-tx-rx{{96}{0}}
>
> Nice.
>
>> > (000.001720) can0 20000080 [8] 00 00 00 00 00 00 68 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{104}{0}}
>> > (000.001876) can0 20000080 [8] 00 00 00 00 00 00 70 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{112}{0}}
>> > (000.001749) can0 20000080 [8] 00 00 00 00 00 00 78 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{120}{0}}
>> > (000.001771) can0 20000084 [8] 00 20 00 00 00 00 80 00
>> > ERRORFRAME
>> > controller-problem{tx-error-passive}
>> Also good.
>> > bus-error
>> > error-counter-tx-rx{{128}{0}}
>
> Also nice :-)
>
>> > (000.001868) can0 20000080 [8] 00 00 00 00 00 00 80 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{128}{0}}
>> > (000.001982) can0 20000080 [8] 00 00 00 00 00 00 80 00
>> > ERRORFRAME
>> > bus-error
>> > error-counter-tx-rx{{128}{0}}
>> >
>> > (( Then a continous flood, exactly similar to the above packet,
>> > appears.
>> > Unfortunately this flooding is a firmware problem. ))
>> >
>> > <-- Replug the cable, after a good amount of time -->
>> >
>> Where are the reverse state transitions?
>> >
>
> Hmmm...
>
> [ ... ]
>>
>> Reverse state transitions are missing from the logs. See comments
above.
>>
>
> When the device is on the _receiving_ end, and I unplug the CAN cable
after
> introducing some noise to the level of reaching WARNING or PASSIVE, I
> receive a BUS_ERROR event with the rxerr count reset back to 0 or 1. In
> that case, the driver correctly transitions back the state to
ERROR_ACTIVE
> and candump produces something similar to:
>
> (000.000362) can0 2000008C [8] 00 40 40 00 00 00 00 01
> ERRORFRAME
> controller-problem{}
> protocol-violation{{back-to-error-active}{}}
> bus-error
> error-counter-tx-rx{{0}{1}}
>
> which is, AFAIK, the correct behaviour from the driver side.
>
> Meanwhile, when the device is on the _sending_ end and I re-plug the CAN
> cable again. Sometimes I receive events with txerr reset to 0 or 1, and
> the driver correctly reverts back to ERROR_ACTIVE in that case. But on
> another times like the quoted case above, I don't receive any events
> resetting txerr back -- only data packets on the bus.

Well, the firmware seems to report *only* bus-errors via
CMD_CAN_ERROR_EVENT
messages, also carrying the new state, but no CMD_CHIP_STATE_EVENT just
for
the state changes.

> So, What can the driver do given the above?

Little if the notification does not come.

Wolfgang.