Re: [PATCH] can: dev: clean up CAN ctrlmode when close CAN device

[Marc Kleine-Budde]

On 4/10/19 8:27 AM, Joakim Zhang wrote:
> CAN driver always writes registers according to "ctrlmode", and now CAN
> framework will keep CAN ctrlmode after device closed.
> 
> e.g. with following sequences:
> 1)ip link set can0 type can bitrate 1000000 loopback on
> 2)ip link set can0 up
> 3)ip link set can0 down
> 4)ip link set can0 type can bitrate 1000000
> 5)ip link set can0 up
> 
> After this sequence, we may want to test loopback for the first time and
> not to test loopback second time. However, CAN device still keep
> "ctrlmode" as loopback on.

Then you should configure loopback off in userspace.

> This patch intends to clean up CAN ctrlmode when close CAN device. We
> can set which ctrlmode we need when open CAN device again.

Consider a CANFD device, where CANFD has been enabled. It will feel very
weird if the interface looses the CANFD property by just a ifdown; ifup.

> 
> Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> ---
>  drivers/net/can/dev.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
> index c05e4d50d43d..4f69a8f16ba3 100644
> --- a/drivers/net/can/dev.c
> +++ b/drivers/net/can/dev.c
> @@ -870,6 +870,7 @@ void close_candev(struct net_device *dev)
>  	struct can_priv *priv = netdev_priv(dev);
>  
>  	cancel_delayed_work_sync(&priv->restart_work);
> +	priv->ctrlmode = 0;
>  	can_flush_echo_skb(dev);
>  }
>  EXPORT_SYMBOL_GPL(close_candev);
> 

Marc

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