netdev - RE: [PATCH 4/6] can: rcar_canfd: Add clk_postdiv to struct rcar_canfd_hw

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Date:   Mon, 24 Oct 2022 17:25:39 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
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>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Stefan Mätje <stefan.maetje@....eu>,
        Ulrich Hecht <uli+renesas@...nd.eu>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        "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 4/6] can: rcar_canfd: Add clk_postdiv to struct
 rcar_canfd_hw_info

Hi Geert,

Thanks for the feedback.

> Subject: Re: [PATCH 4/6] can: rcar_canfd: Add clk_postdiv to struct
> rcar_canfd_hw_info
> 
> Hi Biju,
> 
> On Sat, Oct 22, 2022 at 1:03 PM Biju Das <biju.das.jz@...renesas.com>
> wrote:
> > R-Car has a clock divider for CAN FD clock within the IP, whereas it
> > is not available on RZ/G2L.
> >
> > Add clk_postdiv to struct rcar_canfd_hw_info to take care of this
> > difference.
> >
> > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/net/can/rcar/rcar_canfd.c
> > +++ b/drivers/net/can/rcar/rcar_canfd.c
> > @@ -528,6 +528,7 @@ struct rcar_canfd_hw_info {
> >         u32 max_channels;
> >         /* hardware features */
> >         unsigned multi_global_irqs:1;   /* Has multiple global irqs
> */
> > +       unsigned clk_postdiv:1;         /* Has CAN clk post divider
> */
> 
> As this is not the actual post divider, I think this should be called
> has_clk_postdiv. But see below...

OK will use driver data " postdiv" instead as mentioned below.

> 
> >  };
> >
> >  /* Channel priv data */
> 
> > @@ -1948,7 +1951,7 @@ static int rcar_canfd_probe(struct
> platform_device *pdev)
> >         }
> >         fcan_freq = clk_get_rate(gpriv->can_clk);
> >
> > -       if (gpriv->fcan == RCANFD_CANFDCLK && info->chip_id !=
> RENESAS_RZG2L)
> > +       if (gpriv->fcan == RCANFD_CANFDCLK && info->clk_postdiv)
> >                 /* CANFD clock is further divided by (1/2) within
> the IP */
> >                 fcan_freq /= 2;
> 
> If info->clk_postdiv would be the actual post divider, you could
> simplify to:
> 
>     if (gpriv->fcan == RCANFD_CANFDCLK)
>             fcan_freq /= info->postdiv;


Agreed.

Thanks and regards,
Biju