RE: [PATCH v2 1/4] can: rcar_canfd: Add shared_bittiming variable to struct rcar_canfd_hw_info

[Biju Das]

Hi Geert,

Thanks for the feedback.

> -----Original Message-----
> From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Sent: 01 September 2025 14:16
> Subject: Re: [PATCH v2 1/4] can: rcar_canfd: Add shared_bittiming variable to struct rcar_canfd_hw_info
> 
> Hi Biju,
> 
> On Thu, 21 Aug 2025 at 16:14, Biju <biju.das.au@xxxxxxxxx> wrote:
> > From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> >
> > The calculation formula for nominal bit rate of classical CAN is same
> > as that of nominal bit rate of CANFD on the RZ/G3E SoC compared to other SoCs.
> > Add shared_bittiming variable to struct rcar_canfd_hw_info to handle
> > this difference.
> >
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > Reviewed-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> 
> Thanks for your patch!
> 
> > --- a/drivers/net/can/rcar/rcar_canfd.c
> > +++ b/drivers/net/can/rcar/rcar_canfd.c
> > @@ -461,6 +461,7 @@ struct rcar_canfd_hw_info {
> >         unsigned ch_interface_mode:1;   /* Has channel interface mode */
> >         unsigned shared_can_regs:1;     /* Has shared classical can registers */
> >         unsigned external_clk:1;        /* Has external clock */
> > +       unsigned shared_bittiming:1;    /* Has shared nominal bittiming constants */
> >  };
> >
> >  /* Channel priv data */
> > @@ -632,6 +633,7 @@ static const struct rcar_canfd_hw_info rcar_gen3_hw_info = {
> >         .ch_interface_mode = 0,
> >         .shared_can_regs = 0,
> >         .external_clk = 1,
> > +       .shared_bittiming = 0,
> >  };
> >
> >  static const struct rcar_canfd_hw_info rcar_gen4_hw_info = { @@
> > -649,6 +651,7 @@ static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
> >         .ch_interface_mode = 1,
> >         .shared_can_regs = 1,
> >         .external_clk = 1,
> > +       .shared_bittiming = 0,
> 
> I could find no stricter limitation of the bit timings in classical CAN mode on R-Car Gen4, so it looks
> like this should be 1, too...

Agreed.

> 
> >  };
> >
> >  static const struct rcar_canfd_hw_info rzg2l_hw_info = { @@ -666,6
> > +669,7 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
> >         .ch_interface_mode = 0,
> >         .shared_can_regs = 0,
> >         .external_clk = 1,
> > +       .shared_bittiming = 0,
> >  };
> >
> >  static const struct rcar_canfd_hw_info r9a09g047_hw_info = { @@
> > -683,6 +687,7 @@ static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
> >         .ch_interface_mode = 1,
> >         .shared_can_regs = 1,
> >         .external_clk = 0,
> > +       .shared_bittiming = 1,
> >  };
> >
> >  /* Helper functions */
> > @@ -1912,7 +1917,10 @@ static int rcar_canfd_channel_probe(struct rcar_canfd_global *gpriv, u32 ch,
> >                 priv->can.fd.do_get_auto_tdcv = rcar_canfd_get_auto_tdcv;
> >         } else {
> >                 /* Controller starts in Classical CAN only mode */
> > -               priv->can.bittiming_const = &rcar_canfd_bittiming_const;
> > +               if (gpriv->info->shared_bittiming)
> 
> ... hence you can just check the existing shared_can_regs flag here, and don't need to introduce a new
> flag for shared bittimings?

OK will use existing shared_can_regs flag here.


Cheers,
Biju