netdev - Re: [PATCH] net: dsa: qca8k: fix kernel panic with legacy mdio mapping

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Date:   Sat, 11 Sep 2021 17:36:40 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: dsa: qca8k: fix kernel panic with legacy mdio
 mapping

On Sat, Sep 11, 2021 at 08:31:51AM -0700, Florian Fainelli wrote:
> 
> 
> On 9/11/2021 08:07, Ansuel Smith wrote:
> > When the mdio legacy mapping is used the mii_bus priv registred by DSA
> 
> typo: registered
> 
> > refer to the dsa switch struct instead of the qca8k_priv struct and
> > cause a kernel panic.
> 
> typo: causes
> 
> > Create dedicated function when the internal
> > dedicated mdio driver is used to proprely handle the 2 different
> > implementation.
> 
> typo: properly
> 
> > 
> > Fixes: 759bafb8a322 ("net: dsa: qca8k: add support for internal phy and internal mdio")
> > Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> > ---
> >   drivers/net/dsa/qca8k.c | 30 ++++++++++++++++++++++--------
> >   1 file changed, 22 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> > index 1f63f50f73f1..a701323daf72 100644
> > --- a/drivers/net/dsa/qca8k.c
> > +++ b/drivers/net/dsa/qca8k.c
> > @@ -643,10 +643,8 @@ qca8k_mdio_busy_wait(struct mii_bus *bus, u32 reg, u32 mask)
> >   }
> >   static int
> > -qca8k_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
> > +qca8k_mdio_write(struct mii_bus *bus, int phy, int regnum, u16 data)
> >   {
> > -	struct qca8k_priv *priv = salve_bus->priv;
> > -	struct mii_bus *bus = priv->bus;
> >   	u16 r1, r2, page;
> >   	u32 val;
> >   	int ret;
> > @@ -682,10 +680,8 @@ qca8k_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
> >   }
> >   static int
> > -qca8k_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
> > +qca8k_mdio_read(struct mii_bus *bus, int phy, int regnum)
> >   {
> > -	struct qca8k_priv *priv = salve_bus->priv;
> > -	struct mii_bus *bus = priv->bus;
> >   	u16 r1, r2, page;
> >   	u32 val;
> >   	int ret;
> > @@ -726,6 +722,24 @@ qca8k_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
> >   	return ret;
> >   }
> > +static int
> > +qca8k_internal_mdio_write(struct mii_bus *salve_bus, int phy, int regnum, u16 data)
> > +{
> > +	struct qca8k_priv *priv = salve_bus->priv;
> 
> You are only moving code here but while at it, mind fixing that typo?
>

I think I didn't understand what you mean here.
Sure I will fix the typo and sorry about it.
Aside from that anything wrong with the 2 new function or there is a
better fix that I can't think of.

> > +	struct mii_bus *bus = priv->bus;
> > +
> > +	return qca8k_mdio_write(bus, phy, regnum, data);
> > +}
> > +
> > +static int
> > +qca8k_internal_mdio_read(struct mii_bus *salve_bus, int phy, int regnum)
> > +{
> > +	struct qca8k_priv *priv = salve_bus->priv;
> > +	struct mii_bus *bus = priv->bus;
> > +
> > +	return qca8k_mdio_read(bus, phy, regnum);
> > +}
> > +
> >   static int
> >   qca8k_phy_write(struct dsa_switch *ds, int port, int regnum, u16 data)
> >   {
> > @@ -775,8 +789,8 @@ qca8k_mdio_register(struct qca8k_priv *priv, struct device_node *mdio)
> >   	bus->priv = (void *)priv;
> >   	bus->name = "qca8k slave mii";
> > -	bus->read = qca8k_mdio_read;
> > -	bus->write = qca8k_mdio_write;
> > +	bus->read = qca8k_internal_mdio_read;
> > +	bus->write = qca8k_internal_mdio_write;
> >   	snprintf(bus->id, MII_BUS_ID_SIZE, "qca8k-%d",
> >   		 ds->index);
> > 
> 
> -- 
> Florian