Re: [PATCH RESEND] can: j1939: do not wait 250ms if the same addr was already claimed

[Oleksij Rempel]

Hi,

On Mon, May 09, 2022 at 09:04:06PM +0200, Kurt Van Dijck wrote:
> On ma, 09 mei 2022 19:03:03 +0200, Devid Antonio Filoni wrote:
> > This is not explicitly stated in SAE J1939-21 and some tools used for
> > ISO-11783 certification do not expect this wait.

It will be interesting to know which certification tool do not expect it and
what explanation is used if it fails?

> IMHO, the current behaviour is not explicitely stated, but nor is the opposite.
> And if I'm not mistaken, this introduces a 250msec delay.
> 
> 1. If you want to avoid the 250msec gap, you should avoid to contest the same address.
> 
> 2. It's a balance between predictability and flexibility, but if you try to accomplish both,
> as your patch suggests, there is slight time-window until the current owner responds,
> in which it may be confusing which node has the address. It depends on how much history
> you have collected on the bus.
> 
> I'm sure that this problem decreases with increasing processing power on the nodes,
> but bigger internal queues also increase this window.
> 
> It would certainly help if you describe how the current implementation fails.
> 
> Would decreasing the dead time to 50msec help in such case.
> 
> Kind regards,
> Kurt
> 

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