linux-kernel - Re: [PATCH v2 2/5] can: rcar_canfd: Add support for RZ/G2L family

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Date:   Tue, 20 Jul 2021 15:57:40 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Rob Herring <robh+dt@...nel.org>,
        Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-can@...r.kernel.org,
        netdev <netdev@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v2 2/5] can: rcar_canfd: Add support for RZ/G2L family

Hi Philipp,

Thank you for the review.

On Tue, Jul 20, 2021 at 11:23 AM Philipp Zabel <p.zabel@...gutronix.de> wrote:
>
> On Mon, 2021-07-19 at 15:38 +0100, Lad Prabhakar wrote:
> > CANFD block on RZ/G2L SoC is almost identical to one found on
> > R-Car Gen3 SoC's. On RZ/G2L SoC interrupt sources for each channel
> > are split into different sources and the IP doesn't divide (1/2)
> > CANFD clock within the IP.
> >
> > This patch adds compatible string for RZ/G2L family and registers
> > the irq handlers required for CANFD operation. IRQ numbers are now
> > fetched based on names instead of indices. For backward compatibility
> > on non RZ/G2L SoC's we fallback reading based on indices.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
> > ---
> >  drivers/net/can/rcar/rcar_canfd.c | 178 ++++++++++++++++++++++++------
> >  1 file changed, 147 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
> > index 311e6ca3bdc4..d4affc002fb3 100644
> > --- a/drivers/net/can/rcar/rcar_canfd.c
> > +++ b/drivers/net/can/rcar/rcar_canfd.c
> > @@ -37,9 +37,15 @@
> [...]
> > +     if (gpriv->chip_id == RENESAS_RZG2L) {
> > +             gpriv->rstc1 = devm_reset_control_get_exclusive_by_index(&pdev->dev, 0);
> > +             if (IS_ERR(gpriv->rstc1)) {
> > +                     dev_err(&pdev->dev, "failed to get reset index 0\n");
>
> Please consider requesting the reset controls by name instead of by
> index. See also my reply to the binding patch.
>
Will do.

> > +                     return PTR_ERR(gpriv->rstc1);
> > +             }
> > +
> > +             err = reset_control_reset(gpriv->rstc1);
> > +             if (err)
> > +                     return err;
>
> I suggest to wait until after all resource requests have succeeded
> before triggering the resets, i.e. first get all reset controls and
> clocks, etc., and only then trigger resets, enable clocks, and so on.
>
> That way there will be no spurious resets in case of probe deferrals.
>
Agreed, will update the code.

Cheers,
Prabhakar

> regards
> Philipp