[PATCH] can: netlink: allow configuring of fixed data bit rates without need for do_set_data_bittiming callback

[PATCH] can: netlink: allow configuring of fixed data bit rates without need for do_set_data_bittiming callback

[Marc Kleine-Budde]

This patch is similar to 7e193a42c37c ("can: netlink: allow
configuring of fixed bit rates without need for do_set_bittiming
callback") but for data bit rates instead of bit rates.

Usually CAN devices support configurable data bit rates. The limits
are defined by struct can_priv::data_bittiming_const. Another way is
to implement the struct can_priv::do_set_data_bittiming callback.

If the bit rate is configured via netlink, the can_changelink()
function checks that either can_priv::data_bittiming_const or struct
can_priv::do_set_data_bittiming is implemented.

In commit 431af779256c ("can: dev: add CAN interface API for fixed
bitrates") an API for configuring bit rates on CAN interfaces that
only support fixed bit rates was added. The supported bit rates are
defined by struct can_priv::bitrate_const.

However the above mentioned commit forgot to add the struct
can_priv::data_bitrate_const to the check in can_changelink().

In order to avoid to implement a no-op can_priv::do_set_data_bittiming
callback on devices with fixed data bit rates, extend the check in
can_changelink() accordingly.

Fixes: 431af779256c ("can: dev: add CAN interface API for fixed bitrates")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/netlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 667ddd28fcdc..037824011266 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -279,7 +279,8 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 		 * directly via do_set_bitrate(). Bail out if neither
 		 * is given.
 		 */
-		if (!priv->data_bittiming_const && !priv->do_set_data_bittiming)
+		if (!priv->data_bittiming_const && !priv->do_set_data_bittiming &&
+		    !priv->data_bitrate_const)
 			return -EOPNOTSUPP;
 
 		memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
-- 
2.35.1

Re: [PATCH] can: netlink: allow configuring of fixed data bit rates without need for do_set_data_bittiming callback

[Max Staudt]

I've never used this feature, but I guess it looks good, thanks!

Acked-by: Max Staudt <max@enpas.org>

Re: [PATCH] can: netlink: allow configuring of fixed data bit rates without need for do_set_data_bittiming callback

[Marc Kleine-Budde]

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On 13.06.2022 17:36:43, Max Staudt wrote:
> I've never used this feature, but I guess it looks good, thanks!

It's devices supporting CAN-FD. In CAN-FD you can have 2 different bit
rates. On for the arbitration (beginning of CAN frame) and a faster one
for the data of the CAN frame.

> Acked-by: Max Staudt <max@enpas.org>

Thanks,
Marc

--
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