Re: [PATCH 7/7] drivers: net: macb: add fu740 support

[Green Wan]

Bin Meng <bmeng...@gmail.com>於 2021年3月11日 週四，下午10:22寫道：

> On Thu, Mar 11, 2021 at 9:50 PM Green Wan <green....@sifive.com> wrote:
> >
> > Add fu740 support to macb ethernet driver
> >
> > Signed-off-by: Green Wan <green....@sifive.com>
> > ---
> >  drivers/net/macb.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/macb.c b/drivers/net/macb.c
> > index 57ea45e..df65d82 100644
> > --- a/drivers/net/macb.c
> > +++ b/drivers/net/macb.c
> > @@ -592,7 +592,11 @@ static int macb_sifive_clk_init(struct udevice
> *dev, ulong rate)
> >          *     and output clock on GMII output signal GTX_CLK
> >          * 1 = MII mode. Use MII input signal TX_CLK in TX logic
> >          */
> > -       writel(rate != 125000000, gemgxl_regs);
> > +       if (device_is_compatible(dev, "sifive,fu540-c000-gem"))
> > +               writel(rate != 125000000, gemgxl_regs);
> > +       else if (device_is_compatible(dev, "sifive,fu740-c000-gem"))
> > +               writel(rate != 125125000, gemgxl_regs);
>
> 125125000 seems to be an odd value for 1000 Mbps ethernet. Can you
> please explain this a little bit?


It's simply due to the limitation in the PLL cannot generate 125 000 000 Hz
clock precisely. The closet one is 125 125 000 HZ.


>
> > +
> >         return 0;
> >  }
> >
> > @@ -1507,6 +1511,8 @@ static const struct udevice_id macb_eth_ids[] = {
> >         { .compatible = "cdns,zynq-gem" },
> >         { .compatible = "sifive,fu540-c000-gem",
> >           .data = (ulong)&sifive_config },
> > +       { .compatible = "sifive,fu740-c000-gem",
> > +         .data = (ulong)&sifive_config },
> >         { .compatible = "microchip,mpfs-mss-gem",
> >           .data = (ulong)&microchip_config },
> >         { }
> >
>
> Regards,
> Bin
>