netdev - RE: [PATCH v3 3/6] can: sja1000: Add Quirk for RZ/N1 SJA1000 CAN controller

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Date:   Mon, 4 Jul 2022 10:13:16 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Vincent MAILHOL <mailhol.vincent@...adoo.fr>
CC:     Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Stefan Mätje <stefan.maetje@....eu>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH v3 3/6] can: sja1000: Add Quirk for RZ/N1 SJA1000 CAN
 controller

Hi Vincent,

Thanks for the feedback.

> Subject: Re: [PATCH v3 3/6] can: sja1000: Add Quirk for RZ/N1 SJA1000 CAN
> controller
> 
> Hi Biju,
> 
> I gave a quick look to your series. Nothing odd to me, I just have a
> single nitpick.
> 
> On Mon. 4 juil. 2022 at 16:51, Biju Das <biju.das.jz@...renesas.com>
> wrote:
> > As per Chapter 6.5.16 of the RZ/N1 Peripheral Manual, The SJA1000 CAN
> > controller does not support Clock Divider Register compared to the
> > reference Philips SJA1000 device.
> >
> > This patch adds a device quirk to handle this difference.
> >
> > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> > ---
> > v2->v3:
> >  * No Change
> > v1->v2:
> >  * Updated commit description
> >  * Removed the quirk macro SJA1000_NO_HW_LOOPBACK_QUIRK
> >  * Added prefix SJA1000_QUIRK_* for quirk macro.
> > ---
> >  drivers/net/can/sja1000/sja1000.c | 13 ++++++++-----
> > drivers/net/can/sja1000/sja1000.h |  3 ++-
> >  2 files changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/net/can/sja1000/sja1000.c
> > b/drivers/net/can/sja1000/sja1000.c
> > index 2e7638f98cf1..e9c55f5aa3c3 100644
> > --- a/drivers/net/can/sja1000/sja1000.c
> > +++ b/drivers/net/can/sja1000/sja1000.c
> > @@ -183,8 +183,9 @@ static void chipset_init(struct net_device *dev)
> > {
> >         struct sja1000_priv *priv = netdev_priv(dev);
> >
> > -       /* set clock divider and output control register */
> > -       priv->write_reg(priv, SJA1000_CDR, priv->cdr | CDR_PELICAN);
> > +       if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG))
> > +               /* set clock divider and output control register */
> > +               priv->write_reg(priv, SJA1000_CDR, priv->cdr |
> > + CDR_PELICAN);
> >
> >         /* set acceptance filter (accept all) */
> >         priv->write_reg(priv, SJA1000_ACCC0, 0x00); @@ -208,9 +209,11
> > @@ static void sja1000_start(struct net_device *dev)
> >         if (priv->can.state != CAN_STATE_STOPPED)
> >                 set_reset_mode(dev);
> >
> > -       /* Initialize chip if uninitialized at this stage */
> > -       if (!(priv->read_reg(priv, SJA1000_CDR) & CDR_PELICAN))
> > -               chipset_init(dev);
> > +       if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG)) {
> > +               /* Initialize chip if uninitialized at this stage */
> > +               if (!(priv->read_reg(priv, SJA1000_CDR) &
> > + CDR_PELICAN))
> 
> You can combine the two if in one:
> 
> |        /* Initialize chip if uninitialized at this stage */
> |        if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG ||
> |              priv->read_reg(priv, SJA1000_CDR) & CDR_PELICAN))
> |                chipset_init(dev);
> 
> > +                       chipset_init(dev);
> > +       }

OK, will fix this in next version.

Cheers,
Biju

> >
> >         /* Clear error counters and error code capture */
> >         priv->write_reg(priv, SJA1000_TXERR, 0x0); diff --git
> > a/drivers/net/can/sja1000/sja1000.h
> > b/drivers/net/can/sja1000/sja1000.h
> > index 9d46398f8154..7f736f1df547 100644
> > --- a/drivers/net/can/sja1000/sja1000.h
> > +++ b/drivers/net/can/sja1000/sja1000.h
> > @@ -145,7 +145,8 @@
> >  /*
> >   * Flags for sja1000priv.flags
> >   */
> > -#define SJA1000_CUSTOM_IRQ_HANDLER 0x1
> > +#define SJA1000_CUSTOM_IRQ_HANDLER     BIT(0)
> > +#define SJA1000_QUIRK_NO_CDR_REG       BIT(1)
> >
> >  /*
> >   * SJA1000 private data structure