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Date:   Mon, 18 Jul 2022 12:22:03 +0200
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
Message-ID: <20220718102203.66y6glwwphptl2tu@pengutronix.de>
References: <20220716170007.2020037-1-dario.binacchi@amarulasolutions.com>
 <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.

=2E..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..

>=20
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
>=20
> ---
>=20
>  drivers/net/can/slcan/slcan-core.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
>=20
> diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/s=
lcan-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)
>  			}
>  		}
> =20
> -		err =3D 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 =3D 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 =3D slcan_transmit_cmd(sl, "O\r");
> +			if (err) {
> +				netdev_err(dev,
> +					   "failed to send open command 'O\\r'\n");
> +				goto cmd_transmit_failed;
> +			}
>  		}
>  	}
> =20
> @@ -801,6 +812,7 @@ static int slcan_open(struct tty_struct *tty)
>  	/* Configure CAN metadata */
>  	sl->can.bitrate_const =3D slcan_bitrate_const;
>  	sl->can.bitrate_const_cnt =3D ARRAY_SIZE(slcan_bitrate_const);
> +	sl->can.ctrlmode_supported =3D CAN_CTRLMODE_LISTENONLY;
> =20
>  	/* Configure netdev interface */
>  	sl->dev	=3D dev;

Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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