On 09/27/2011 07:32 PM, Oliver Hartkopp wrote: > On 09/24/11 09:22, Wolfgang Grandegger wrote: > >> On 09/23/2011 11:32 AM, Pavel Pisa wrote: > >>> On base of above analysis, I think that blindly set SJW >>> on maximum is not good idea. It should be at least limited >>> to 5% of bit time. > > > (..) > > >>> SJW is more problematic, but may it be use of 2 or 5% >>> of bittime by default with assurance that zero is >>> replaced by one, would serve to most people pleasure. > > > (..) > >>> But there is still unknown parameter >>> capacity/length of connected wires so there is still >>> something left to user consideration. >> >> Thanks for your detailed explanation. It clearly shows that adjusting >> SJW is non-trivial and nothing a normal CAN user should deal with. When >> adjusting SJW, do you also need to tweek other bit-timing parameters, >> e.g. tq? I mean, would "ip link set can0 type can bitrate x >> sampling-point y sjw z" work for your setup or do you need to use the >> expert mode setting via "ip link set can0 type can tq ..." anyway? > > > Hello Wolfgang, > > i double checked a specification where i got my requirement to influence the > SJW value from. It says (non literally): > > "Put the SJW to the highest possible value only reduced by tseg2." > > The fact that this requirement might no fit to any CAN setup or may not be in > best academical shape is not my problem. My requirement is to provide an easy > way to move the SJW away from it's default value, which is currently > hard-coded to 1 in the can-dev framework when using it's bittiming calculation > function.
OK. > As almost everything is already done (only the provided SJW is not evaluated > in dev.c) this patch is IMO an valid option to support it. If Joe user can > tune the sampling point, why should he not be able to influence the SJW if he > thinks, he knows what he's doing? > > Especially as the good working bittiming calculation is not touched in any way > and the default SJW remains 1 (even if '0' is provided as user input). Still not sure if it's useful. Anyway, just added my acked-by to your patch. Thanks, Wolfgang. _______________________________________________ Socketcan-core mailing list Socketcan-core@lists.berlios.de https://lists.berlios.de/mailman/listinfo/socketcan-core
