netdev - Re: [RFC PATCH 00/13] can: slcan: extend supported features

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Date:   Tue, 7 Jun 2022 19:27:05 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
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>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Paolo Abeni <pabeni@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH 00/13] can: slcan: extend supported features

On Tue. 7 juin 2022 at 18:47, Dario Binacchi
<dario.binacchi@...rulasolutions.com> wrote:
> This series originated as a result of CAN communication tests for an
> application using the USBtin adapter (https://www.fischl.de/usbtin/).
> The tests showed some errors but for the driver everything was ok.
> Also, being the first time I used the slcan driver, I was amazed that
> it was not possible to configure the bitrate via the ip tool.
> For these two reasons, I started looking at the driver code and realized
> that it didn't use the CAN network device driver interface.

That's funny! Yesterday, I sent this comment:
https://lore.kernel.org/linux-can/CAMZ6RqKZwC_OKcgH+WPacY6kbNbj4xR2Gdg2NQtm5Ka5Hfw79A@mail.gmail.com/

And today, you send a full series to remove all the dust from the
slcan driver. Do I have some kind of mystical power to summon people
on the mailing list?

> Starting from these assumptions, I tried to:
> - Use the CAN network device driver interface.

In order to use the CAN network device driver, a.k.a. can-dev module,
drivers/net/can/Kbuild has to be adjusted: move slcan inside CAN_DEV
scope.

@Mark: because I will have to send a new version for my can-dev/Kbuild
cleanup, maybe I can take that change and add it to my series?

> - Set the bitrate via the ip tool.
> - Send the open/close command to the adapter from the driver.
> - Add ethtool support to reset the adapter errors.
> - Extend the protocol to forward the adapter CAN communication
>   errors and the CAN state changes to the netdev upper layers.
>
> Except for the protocol extension patches (i. e. forward the adapter CAN
> communication errors and the CAN state changes to the netdev upper
> layers), the whole series has been tested. Testing the extension
> protocol patches requires updating the adapter firmware. Before modifying
> the firmware I think it makes sense to know if these extensions can be
> considered useful.
>
> Before applying the series I used these commands:
>
> slcan_attach -f -s6 -o /dev/ttyACM0
> slcand ttyACM0 can0
> ip link set can0 up
>
> After applying the series I am using these commands:
>
> slcan_attach /dev/ttyACM0
> slcand ttyACM0 can0
> ip link set dev can0 down
> ip link set can0 type can bitrate 500000
> ethtool --set-priv-flags can0 err-rst-on-open on
> ip link set dev can0 up
>
> Now there is a clearer separation between serial line and CAN,
> but above all, it is possible to use the ip and ethtool commands
> as it happens for any CAN device driver. The changes are backward
> compatible, you can continue to use the slcand and slcan_attach
> command options.
>
>
>
> Dario Binacchi (13):
>   can: slcan: use the BIT() helper
>   can: slcan: use netdev helpers to print out messages
>   can: slcan: use the alloc_can_skb() helper
>   can: slcan: use CAN network device driver API
>   can: slcan: simplify the device de-allocation
>   can: slcan: allow to send commands to the adapter
>   can: slcan: set bitrate by CAN device driver API
>   can: slcan: send the open command to the adapter
>   can: slcan: send the close command to the adapter
>   can: slcan: move driver into separate sub directory
>   can: slcan: add ethtool support to reset adapter errors
>   can: slcan: extend the protocol with error info
>   can: slcan: extend the protocol with CAN state info
>
>  drivers/net/can/Makefile                      |   2 +-
>  drivers/net/can/slcan/Makefile                |   7 +
>  .../net/can/{slcan.c => slcan/slcan-core.c}   | 464 +++++++++++++++---
>  drivers/net/can/slcan/slcan-ethtool.c         |  65 +++
>  drivers/net/can/slcan/slcan.h                 |  18 +
>  5 files changed, 480 insertions(+), 76 deletions(-)
>  create mode 100644 drivers/net/can/slcan/Makefile
>  rename drivers/net/can/{slcan.c => slcan/slcan-core.c} (67%)
>  create mode 100644 drivers/net/can/slcan/slcan-ethtool.c
>  create mode 100644 drivers/net/can/slcan/slcan.h