Re: [PATCH v5 4/6] can: introduce the data bitrate configuration for CAN FD

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 02/26/2014 11:11 PM, Oliver Hartkopp wrote:
> As CAN FD offers a second bitrate for the data section of the CAN frame the
> infrastructure for storing and configuring this second bitrate is introduced.
> 
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> ---
>  drivers/net/can/dev.c            | 42 +++++++++++++++++++++++++++++++++++++++-
>  include/linux/can/dev.h          |  6 ++++--
>  include/uapi/linux/can/netlink.h |  2 ++
>  3 files changed, 47 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
> index 368d92d..7887691 100644
> --- a/drivers/net/can/dev.c
> +++ b/drivers/net/can/dev.c
> @@ -660,6 +660,10 @@ static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
>  				= { .len = sizeof(struct can_bittiming_const) },
>  	[IFLA_CAN_CLOCK]	= { .len = sizeof(struct can_clock) },
>  	[IFLA_CAN_BERR_COUNTER]	= { .len = sizeof(struct can_berr_counter) },
> +	[IFLA_CAN_DATA_BITTIMING]
> +				= { .len = sizeof(struct can_bittiming) },
> +	[IFLA_CAN_DATA_BITTIMING_CONST]
> +				= { .len = sizeof(struct can_bittiming_const) },
>  };
>  
>  static int can_changelink(struct net_device *dev,
> @@ -693,6 +697,29 @@ static int can_changelink(struct net_device *dev,
>  		}
>  	}
>  
> +	if (data[IFLA_CAN_DATA_BITTIMING]) {
> +		struct can_bittiming bt;
> +
> +		/* Do not allow changing bittiming while running */
> +		if (dev->flags & IFF_UP)
> +			return -EBUSY;
> +		memcpy(&bt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
> +		       sizeof(bt));
> +		if ((!bt.bitrate && !bt.tq) || (bt.bitrate && bt.tq))
> +			return -EINVAL;
> +		err = can_get_bittiming(dev, &bt, priv->data_bittiming_const);
> +		if (err)
> +			return err;
> +		memcpy(&priv->data_bittiming, &bt, sizeof(bt));
> +
> +		if (priv->do_set_data_bittiming) {
> +			/* Finally, set the bit-timing registers */
> +			err = priv->do_set_data_bittiming(dev);
> +			if (err)
> +				return err;
> +		}

Do we really need the do_set_data_bittiming() callback? Allmost all
drivers set the bitrate during open and not asynchronously (when the
interface is down) via the set_bittiming() callback. If there is a
driver which really needs this callback, we can introduce it.

Marc

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