On 06/14/2018 08:32 AM, Wolfgang Grandegger wrote:
> Hello Oliver,
>
> Am 14.06.2018 um 07:36 schrieb Oliver Hartkopp:
>> On 06/12/2018 05:06 PM, Wolfgang Grandegger wrote:
>>
>>>>> Is tseg2 always greater than zero at this point? This depends on
>>>>> btc->tseg2_min now which is given by the CAN driver, right?
>>>>
>>>> If we ever get tseg2 equal to zero we get inconsistant configuration
>>>> anyway
>>>> because:
>>>> 1. "bt->phase_seg2 = tseg2" => Phase_Seg2 = 0
>>>> 2. if user set SJW value, we would get SJW = 0 by following code:
>>>> if (tseg2 < bt->sjw)
>>>> bt->sjw = tseg2;
>>>>
>>>> I can add some code to check for configuration consistancy according
>>>> to ISO 11898-1.
>>
>> see below (at the end)
>>
>>>> This should be a separate patch anyway, because while SJW value is
>>
>> right
>>
>>>> debatable there
>>>> are clear requirements on Phase_Seg1, Phase_Seg2 and SJW values at the
>>>> ISO 11898-1.
>>>>
>>>>> This comment has to be adapted or shortened and we need to make sure
>>>>> that
>>>>> sjw remains at least 1 - even when tseg2_min is zero.
>>>>
>>>> Could you please help we truncating the comment?
>>
>> I was thinking about something like this:
>>
>> (..)
>> /* set sjw at least to 1 (min tseg2) if there are no user settings */
>
>> if (!bt->sjw)
>> bt->sjw = tseg2;
>> (..)
>
> We could use:
>
> /* check for sjw user settings */
> if (bt->sjw && btc->sjw_max) {
> /* sanitize upper bound to sjw_max */
> if (bt->sjw > btc->sjw_max)
> bt->sjw = btc->sjw_max;
> /* bt->sjw must not be higher than tseg2 */
> if (tseg2 < bt->sjw)
> bt->sjw = tseg2;
> }
> /* according to ISO 11898-1, sjw should be at least 1 */
> if (!bt->sjw || !btc->sjw_max)
> bt->sjw = 1;
>
> Kind of paranoia, because tseg2_min and sjw_max is never 0. But we
> need to check sjw anyway.
What's the status of this patch?
Marc
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