Re: [PATCH v4 7/7] can: add bittiming check at interface open for CAN FD

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 26.02.2014 20:52, Kurt Van Dijck wrote:

>> +	/* For CAN FD the data bitrate has to be >= the arbitration bitrate */
>> +	if ((priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
>> +	    (!priv->data_bittiming.tq || !priv->data_bittiming.bitrate ||
>> +	     (priv->data_bittiming.bitrate < priv->bittiming.bitrate))) {
> 
> This prevents to configure a data bitrate slower than the arbitration bitrate.
> Such configuration is useless, but is it really "incorrect" or wrong?

Yes it is.

There was a definition that the data bitrate has to be greater or equal the
arbitration bitrate.

In the Bosch whitepaper about CAN FD Florian Hartwich always states about the
higher bitrate - but at least the data bitrate must not be lower than the
arbitration bitrate.

Regards,
Oliver