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

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Date:   Thu, 22 Dec 2022 09:46:48 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Frank Jungclaus <Frank.Jungclaus@....eu>
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. 22 Dec. 2022 at 02:55, Frank Jungclaus <Frank.Jungclaus@....eu> wrote:
> 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.

Thanks for the link. It is indeed compliant.

Reviewed-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>

> >   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
> > >
>