Re: [PATCH v4 4/6] can: flexcan: Consolidate and unify state change handling.

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 12/01/2014 08:42 PM, Wolfgang Grandegger wrote:
[...]
>> Yes. In any case, the warning interrupt is irrelevant, because we have to poll
>> the state anyway for the other states. Thus the FLEXCAN_HAS_BROKEN_ERR_STATE
>> flag is irrelevant.
> 
> Well, it improves the situation a little bit. But now I understand your
> point. Yes the Flexcan core is buggy in this respect.

Yes, just a bit :) This is probably why they added the m_can core on the
new imx6 soloX.

>> The question that remains is: Should we enable bus error interrupts for all
>> flexcan cores or should we ignore the issue and allow the users to work around
>> it (if they wish) using the berr-reporting flag?
> 
> Bus error reporting sometimes really harms and therefore I would leave
> it as-is. There are also more recent cores and it would be nice to known
> if they have improved the reporting of state changes further. Anyway,
> this issue should be addressed by a separate patch series.

>> There is a middle-ground here: We could enable bus error interrupts when we get
>> the error-warning interrupt and disable them again when the state has reached
>> error-active again. In that case we would want to keep the BROKEN_ERR_STATE
>> flag.
> 
> Puh, that's far too sophisticated.

I agree with Wolfgang. The Bus errors can make a system unresponsive to
unusable. There is still the bus error limiting patch lurking around,
which works around this problem.

regards,
Marc
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