netdev - Re: [PATCH 4/6] can: esd_usb: Improved behavior on esd CAN_ERROR

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Message-ID: <CAMZ6Rq+QBO1yTX_o6GV0yhdBj-RzZSRGWDZBS0fs7zbSTy4hmA@mail.gmail.com>
Date:   Tue, 12 Jul 2022 23:39:28 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Frank Jungclaus <frank.jungclaus@....eu>
Cc:     linux-can@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Stefan Mätje <stefan.maetje@....eu>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] can: esd_usb: Improved behavior on esd CAN_ERROR_EXT
 event (3)

On Tue. 9 Jul. 2022 at 03:15, Frank Jungclaus <frank.jungclaus@....eu> wrote:
> Started a rework initiated by Vincents remark about "You should not
> report the greatest of txerr and rxerr but the one which actually
> increased." Now setting CAN_ERR_CRTL_[RT]X_WARNING and
> CAN_ERR_CRTL_[RT]X_PASSIVE depending on REC and TEC
>
> Signed-off-by: Frank Jungclaus <frank.jungclaus@....eu>
> ---
>  drivers/net/can/usb/esd_usb.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
> index 0a402a23d7ac..588caba1453b 100644
> --- a/drivers/net/can/usb/esd_usb.c
> +++ b/drivers/net/can/usb/esd_usb.c
> @@ -304,11 +304,17 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
>                         /* Store error in CAN protocol (location) in data[3] */
>                         cf->data[3] = ecc & SJA1000_ECC_SEG;
>
> -                       if (priv->can.state == CAN_STATE_ERROR_WARNING ||
> -                           priv->can.state == CAN_STATE_ERROR_PASSIVE) {
> -                               cf->data[1] = (txerr > rxerr) ?
> -                                       CAN_ERR_CRTL_TX_PASSIVE :
> -                                       CAN_ERR_CRTL_RX_PASSIVE;
> +                       /* Store error status of CAN-controller in data[1] */
> +                       if (priv->can.state == CAN_STATE_ERROR_WARNING) {
> +                               if (txerr >= 96)
> +                                       cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;

As far as I understand, those flags should be set only when the
threshold is *reached*:
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/can/error.h#L69

I don't think you should set it if the error state does not change.

Here, you probably want to compare the new value  with the previous
one (stored in struct can_berr_counter) to decide whether or not the
flags should be set.


> +                               if (rxerr >= 96)
> +                                       cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
> +                       } else if (priv->can.state == CAN_STATE_ERROR_PASSIVE) {
> +                               if (txerr >= 128)
> +                                       cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
> +                               if (rxerr >= 128)
> +                                       cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
>                         }
>
>                         cf->data[6] = txerr;
> --
> 2.25.1
>