netdev - Re: [PATCH 1/3] can: esd_usb: Improved behavior on esd CAN_ERROR

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Message-ID: <f9c68625149673fec635d64a21608f3b53866cd7.camel@esd.eu>
Date:   Wed, 21 Dec 2022 17:55:02 +0000
From:   Frank Jungclaus <Frank.Jungclaus@....eu>
To:     "mailhol.vincent@...adoo.fr" <mailhol.vincent@...adoo.fr>
CC:     Stefan Mätje <Stefan.Maetje@....eu>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "mkl@...gutronix.de" <mkl@...gutronix.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "wg@...ndegger.com" <wg@...ndegger.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] can: esd_usb: Improved behavior on esd CAN_ERROR_EXT
 event (1)

On Tue, 2022-12-20 at 14:16 +0900, Vincent MAILHOL wrote:
> On Tue. 20 Dec. 2022 at 06:25, Frank Jungclaus <frank.jungclaus@....eu> wrote:
> > 
> > Moved the supply for cf->data[3] (bit stream position of CAN error)
> > outside of the "switch (ecc & SJA1000_ECC_MASK){}"-statement, because
> > this position is independent of the error type.
> > 
> > Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
> > Signed-off-by: Frank Jungclaus <frank.jungclaus@....eu>
> > ---
> >  drivers/net/can/usb/esd_usb.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
> > index 42323f5e6f3a..5e182fadd875 100644
> > --- a/drivers/net/can/usb/esd_usb.c
> > +++ b/drivers/net/can/usb/esd_usb.c
> > @@ -286,7 +286,6 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
> >                                 cf->data[2] |= CAN_ERR_PROT_STUFF;
> >                                 break;
> >                         default:
> > -                               cf->data[3] = ecc & SJA1000_ECC_SEG;
> >                                 break;
> >                         }
> > 
> > @@ -294,6 +293,9 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
> >                         if (!(ecc & SJA1000_ECC_DIR))
> >                                 cf->data[2] |= CAN_ERR_PROT_TX;
> > 
> > +                       /* Bit stream position in CAN frame as the error was detected */
> > +                       cf->data[3] = ecc & SJA1000_ECC_SEG;
> 
> Can you confirm that the value returned by the device matches the
> specifications from linux/can/error.h?

The value returned is supposed to be compatible to the SJA1000 ECC
register.

See
https://esd.eu/fileadmin/esd/docs/manuals/NTCAN_Part1_Function_API_Manual_en_56.pdf

Chapter "6.2.10 EV_CAN_ERROR_EXT" (page 185)
and 
"Annex B: Bus Error Code" table 37 and 38 (page 272 and following).

So this should be compliant with the values given in linux/can/error.h.


> 
>   https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/can/error.h#L90
> 
> >                         if (priv->can.state == CAN_STATE_ERROR_WARNING ||
> >                             priv->can.state == CAN_STATE_ERROR_PASSIVE) {
> >                                 cf->data[1] = (txerr > rxerr) ?
> > --
> > 2.25.1
> >