netdev - Re: [RFC PATCH 06/13] can: slcan: allow to send commands to the adapter

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Date:   Sat, 11 Jun 2022 23:43:47 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Amarula patchwork <linux-amarula@...rulasolutions.com>,
        michael@...rulasolutions.com,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH 06/13] can: slcan: allow to send commands to the adapter

Hi Marc,

On Thu, Jun 9, 2022 at 9:16 AM Marc Kleine-Budde <mkl@...gutronix.de> wrote:
>
> On 07.06.2022 11:47:45, Dario Binacchi wrote:
> > This is a preparation patch for the upcoming support to change the
> > bitrate via ip tool, reset the adapter error states via the ethtool API
> > and, more generally, send commands to the adapter.
> >
> > Since some commands (e. g. setting the bitrate) will be sent before
> > calling the open_candev(), the netif_running() will return false and so
> > a new flag bit (i. e. SLF_XCMD) for serial transmission has to be added.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
>
> I think this patch can be dropped, let me explain:
>
> You don't have to implement the do_set_bittiming callback. It's
> perfectly OK to set the bitrate during the ndo_open callback after
> open_candev().

I developed what you suggested (i. e. remove the SLF_XCMD bit and set the
bitrate, as well as send the "F\r" and "O\r" commands, after calling
the open_candev(),
but now I can't send the close command ("C\r") during the ndo_stop() since
netif_running() returns false. The CAN framework clears netif_running() before
calling the ndo_stop(). IMHO the SLF_XCMD bit then becomes necessary to
transmit the commands to the adapter from the ndo_open() and
ndo_stop() routines.
Any suggestions ?

Thanks and regards,
Dario
>
> regards,
> Marc
>
> --
> 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 |



-- 

Dario Binacchi

Embedded Linux Developer

dario.binacchi@...rulasolutions.com

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