netdev - Re: [RFC PATCH 11/13] can: slcan: add ethtool support to reset adapter errors

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Date:   Fri, 10 Jun 2022 12:51:09 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Dario Binacchi <dario.binacchi@...rulasolutions.com>
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>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH 11/13] can: slcan: add ethtool support to reset
 adapter errors

On 09.06.2022 10:52:03, Dario Binacchi wrote:
> > > The help option of slcan_attach and slcand prints " -f (read status
> > > flags with 'F\\r' to reset error states)\n" I looked at the sources of
> > > the adapter I am using (USBtin, which uses the mcp2515 controller).
> > > The 'F' command reads the EFLG register (0x2d) without resetting the
> > > RX0OVR and RX1OVR overrun bits.
> >
> > The Lawicel doc [1] says 'F' is to read the status flags not to clear
> > it. However commit 7ef581fec029 ("slcan_attach: added '-f' commandline
> > option to read status flags") [2] suggests that there are some adapters
> > that the reading of the status flag clears the errors. IMHO the 'F'
> > command should be send unconditionally during open.
> 
> When in doubt I would follow the slcand / slcan_attach approach, that don't
> send the 'F \ r' command by default. We would be more backward compatible
> as regards the sequence of commands to be sent to the controller.

Ok, keep it this way.

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 |

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