Re: [RFC PATCH 5/5] can: slcan: send the listen-only command to the adapter - Marc Kleine-Budde

From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: linux-kernel@vger.kernel.org,
	Jeroen Hofstee <jhofstee@victronenergy.com>,
	michael@amarulasolutions.com,
	Amarula patchwork <linux-amarula@amarulasolutions.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
	Wolfgang Grandegger <wg@grandegger.com>,
	linux-can@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [RFC PATCH 5/5] can: slcan: send the listen-only command to the adapter
Date: Mon, 18 Jul 2022 12:22:03 +0200	[thread overview]
Message-ID: <20220718102203.66y6glwwphptl2tu@pengutronix.de> (raw)
In-Reply-To: <20220716170007.2020037-6-dario.binacchi@amarulasolutions.com>

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The subject can be enhanced, as the listen-only command ist not send
unconditionally. What about: "add support for listen-only mode"?

On 16.07.2022 19:00:07, Dario Binacchi wrote:
> In case the bitrate has been set via ip tool, this patch changes the
> driver to send the listen-only ("L\r") command to the adapter.

...but only of CAN_CTRLMODE_LISTENONLY is requested.

What about:

For non-legacy, i.e. ip based configuration, add support for listen-only
mode. If listen-only is requested send a listen-only ("L\r") command
instead of an open ("O\r") command to the adapter..

> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> 
> ---
> 
>  drivers/net/can/slcan/slcan-core.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
> index 7a1540507ecd..d97dfeccbf9c 100644
> --- a/drivers/net/can/slcan/slcan-core.c
> +++ b/drivers/net/can/slcan/slcan-core.c
> @@ -711,10 +711,21 @@ static int slcan_netdev_open(struct net_device *dev)
>  			}
>  		}
>  
> -		err = slcan_transmit_cmd(sl, "O\r");
> -		if (err) {
> -			netdev_err(dev, "failed to send open command 'O\\r'\n");
> -			goto cmd_transmit_failed;
> +		/* listen-only command overrides open command */

I think this comment can be removed.

> +		if (sl->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
> +			err = slcan_transmit_cmd(sl, "L\r");
> +			if (err) {
> +				netdev_err(dev,
> +					   "failed to send listen-only command 'L\\r'\n");
> +				goto cmd_transmit_failed;
> +			}
> +		} else {
> +			err = slcan_transmit_cmd(sl, "O\r");
> +			if (err) {
> +				netdev_err(dev,
> +					   "failed to send open command 'O\\r'\n");
> +				goto cmd_transmit_failed;
> +			}
>  		}
>  	}
>  
> @@ -801,6 +812,7 @@ static int slcan_open(struct tty_struct *tty)
>  	/* Configure CAN metadata */
>  	sl->can.bitrate_const = slcan_bitrate_const;
>  	sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
> +	sl->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
>  
>  	/* Configure netdev interface */
>  	sl->dev	= dev;

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
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