linux-kernel - Re: [PATCH] net: mv643xx_eth: support MII/GMII/RGMII modes

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Date:   Fri, 30 Sep 2022 23:05:06 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Yangfl <mmyangfl@...il.com>
Cc:     Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: mv643xx_eth: support MII/GMII/RGMII modes

On Sat, Oct 01, 2022 at 04:47:42AM +0800, Yangfl wrote:
> Andrew Lunn <andrew@...n.ch> 于2022年10月1日周六 04:28写道：
> >
> > On Sat, Oct 01, 2022 at 03:49:23AM +0800, David Yang wrote:
> > > On device reset all ports are automatically set to RGMII mode. MII
> > > mode must be explicitly enabled.
> > >
> > > If SoC has two Ethernet controllers, by setting both of them into MII
> > > mode, the first controller enters GMII mode, while the second
> > > controller is effectively disabled. This requires configuring (and
> > > maybe enabling) the second controller in the device tree, even though
> > > it cannot be used.
> > >
> > > Signed-off-by: David Yang <mmyangfl@...il.com>
> > > ---
> > >  drivers/net/ethernet/marvell/mv643xx_eth.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
> > > index b6be0552a..e2216ce5e 100644
> > > --- a/drivers/net/ethernet/marvell/mv643xx_eth.c
> > > +++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
> > > @@ -108,6 +108,7 @@ static char mv643xx_eth_driver_version[] = "1.4";
> > >  #define TXQ_COMMAND                  0x0048
> > >  #define TXQ_FIX_PRIO_CONF            0x004c
> > >  #define PORT_SERIAL_CONTROL1         0x004c
> > > +#define  RGMII_EN                    0x00000008
> > >  #define  CLK125_BYPASS_EN            0x00000010
> > >  #define TX_BW_RATE                   0x0050
> > >  #define TX_BW_MTU                    0x0058
> > > @@ -1245,6 +1246,21 @@ static void mv643xx_eth_adjust_link(struct net_device *dev)
> > >
> > >  out_write:
> > >       wrlp(mp, PORT_SERIAL_CONTROL, pscr);
> > > +
> > > +     /* If two Ethernet controllers present in the SoC, MII modes follow the
> > > +      * following matrix:
> > > +      *
> > > +      * Port0 Mode   Port1 Mode      Port0 RGMII_EN  Port1 RGMII_EN
> > > +      * RGMII        RGMII           1               1
> > > +      * RGMII        MII/MMII        1               0
> > > +      * MII/MMII     RGMII           0               1
> > > +      * GMII         N/A             0               0
> > > +      *
> > > +      * To enable GMII on Port 0, Port 1 must also disable RGMII_EN too.
> > > +      */
> > > +     if (!phy_interface_is_rgmii(dev->phydev))
> > > +             wrlp(mp, PORT_SERIAL_CONTROL1,
> > > +                  rdlp(mp, PORT_SERIAL_CONTROL1) & ~RGMII_EN);
> >
> > I could be reading this wrong, but doesn't this break the third line:
> >
> > > +      * MII/MMII     RGMII           0               1
> >
> > Port 1 probes first, phy_interface is rgmii, so nothing happens, port1
> > RGMII_EN is left true.
> >
> > Port 0 then probes, MII/MMII is not RGMII, so port1 RGMII_EN is
> > cleared, breaking port1.
> >
> > I think you need to be more specific with the comparison.
> >
> >   Andrew
> 
> Oh, I see. So you mean "phy-mode" property should belong to
> controller, not port? I thought one controller can have at most one
> port.

If you look at mv643xx_eth_shared_of_probe(), it appears a controller
can have multiple ports. And:

        if (dev_num == 3) {
                dev_err(&pdev->dev, "too many ports registered\n");
                return -EINVAL;
        }

I don't know the details?

	Andrew