netdev - Re: [PATCH net-next v2 2/3] net: dsa: mv88e6xxx: add support for bridge flags

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Message-ID: <20190219162435.f5zl5harbarwy6bj@shell.armlinux.org.uk>
Date:   Tue, 19 Feb 2019 16:24:35 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Vivien Didelot <vivien.didelot@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/3] net: dsa: mv88e6xxx: add support for
 bridge flags

On Tue, Feb 19, 2019 at 11:16:12AM -0500, Vivien Didelot wrote:
> Hi Russell,
> 
> On Sun, 17 Feb 2019 16:32:34 +0000, Russell King <rmk+kernel@...linux.org.uk> wrote:
> > +static int mv88e6xxx_port_bridge_flags(struct dsa_switch *ds, int port,
> > +				       unsigned long flags)
> > +{
> > +	struct mv88e6xxx_chip *chip = ds->priv;
> > +	bool unicast, multicast;
> > +	int ret = -EOPNOTSUPP;
> > +
> > +	unicast = dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port) ||
> > +		flags & BR_FLOOD;
> > +	multicast = flags & BR_MCAST_FLOOD;
> > +
> > +	mutex_lock(&chip->reg_lock);
> > +	if (chip->info->ops->port_set_egress_floods)
> > +		ret = chip->info->ops->port_set_egress_floods(chip, port,
> > +							      unicast,
> > +							      multicast);
> > +	mutex_unlock(&chip->reg_lock);
> > +
> > +	return ret;
> > +}
> > +
> > +static unsigned long mv88e6xxx_bridge_flags_support(struct dsa_switch *ds)
> > +{
> > +	struct mv88e6xxx_chip *chip = ds->priv;
> > +	unsigned long support = 0;
> > +
> > +	if (chip->info->ops->port_set_egress_floods)
> > +		support |= BR_FLOOD | BR_MCAST_FLOOD;
> > +
> > +	return support;
> > +}
> 
> I think that it isn't necessary to propagate the notion of bridge flags down
> to the DSA drivers. It might be just enough to add:
> 
>     port_egress_flood(dsa_switch *ds, int port, bool uc, bool mc)
> 
> to dsa_switch_ops and set BR_FLOOD | BR_MCAST_FLOOD from the DSA core,
> if the targeted driver has ds->ops->port_set_egress_flood. What do you think?

There are two other flags that I haven't covered which the bridge code
expects to be offloaded, and those are the broadcast flood flag and
the learning flag.

I know that the Marvell switches don't have a bit to control the
broadcast flooding, that appears to be controlled via a static entry
in the ATU which would have to be modified as the broadcast flood flag
is manipulated.  I don't know how that is handled in other bridges.

Do we want to include the broadcast flood in the above prototype?
If we go for this, how do we detect which options a switch supports?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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