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    SubjectRe: [RFC PATCH 00/13] can: slcan: extend supported features
    +CC: Max Staudt <max@enpas.org>

    On Tue. 7 Jun. 2022 at 18:47, Dario Binacchi
    <dario.binacchi@amarulasolutions.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.
    >
    > Starting from these assumptions, I tried to:
    > - Use the CAN network device driver interface.
    > - 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

    In his CAN327 driver, Max manages to bring the can0 device without the
    need of dedicated user space daemon by using line discipline
    (ldattach):
    https://lore.kernel.org/linux-can/20220602213544.68273-1-max@enpas.org/

    Isn't the same feasible with slcan so that we completely remove the
    dependency toward slcand?
    Max what do you think of this?

    > 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.

    Yours sincerely,
    Vincent Mailhol

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