Kurt Van Dijck wrote:
> On Mon, Feb 08, 2010 at 10:12:12AM +0100, Wolfgang Grandegger wrote:
>> Kurt Van Dijck wrote:
>>> On Sun, Feb 07, 2010 at 06:25:39PM +0100, Wolfgang Grandegger wrote:
>>>> christian pellegrin wrote:
>>>>> On Sun, Feb 7, 2010 at 6:05 PM, Wolfgang Grandegger <[email protected]> 
>>>>> wrote:
>>>>>> christian pellegrin wrote:
>>>>>> increase). Can you confirm that? Normal state changes are interrupt
>>>>>> driver. So, if the hardware does not trigger an interrupt, we have a
>>>>>> problem.
>>>>> On the mcp251x we get an interrupt when we get back from error-warning
>>>>> to error-active but I don't know if we have to send some kind of error
>>>>> frame in this case. Now nothing is sent, I was worried if this is
>>>>> right.
>>>> Good question. I think we should send an error message for any state
>>>> change also for passive->warning->active, which we currently do not
>>>> handle by software. We speak about controller *problems* and there is
>>>> currently no CAN_ERR_CRTL_ACTIVE. Well, that's another weak point :-(.
>>>> This needs some more thoughts/discussion.
>>> We had some discussion lately, but having an interrupt (and some message
>>>    to userspace) seems like a non-optional requirement to me.
>> I don't understand. What is "non-optional"? Currently we just report
>> controller *problems*, meaning state changes
>> active->warning->passive->bus-off.
> sorry for the confusion.
> I meant: having an 'bus state change' interrupt seems a requirement to
> me (therefore : non-optional, but it depends on CAN chip capabilities).
> This (bus-state-change interrupt) is, IMO, more important than the bus
> error interrupts.

Of course. I'm not speaking about the bus-error interrupts here. The
discussion drifted away and the subject is not appropriate anymore :-(.
The question I rised is if we should report state changes
passive->warning->active to the app as well.

> Therefore, I think that it may not be very good not sending anything
> on the 'error-warning to error-active interrupt', as was mentioned
> above.

OK.

> Implementing bus-error interrupts, but poor bus state change interrupts
> requires the user to enable bus-error interrupts, and tracking the bus
> state itself. I do not like that (But I did no mcp251x work either).

The bus-error messages should *not* be used for that purpose. They are
mainly useful to get more information on the cause of the problem (error
type, etc.). As the mcp251x does not provide enhanced information, I do
not regard the bus-error messages for that processor as really useful.

> I think we agree, but I didn't express my opinion very clear :-)

Should be cleared now.

Wolfgang.


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