netdev - Re: [PATCH net-next 1/3] net: dsa: add support for bridge flags

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Date:   Sun, 17 Feb 2019 14:07:54 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/3] net: dsa: add support for bridge flags



On 2/17/2019 2:04 PM, Russell King - ARM Linux admin wrote:
> On Sun, Feb 17, 2019 at 01:37:19PM -0800, Florian Fainelli wrote:
>>
>>
>> On 2/17/2019 6:25 AM, Russell King wrote:
>>> The Linux bridge implementation allows various properties of the bridge
>>> to be controlled, such as flooding unknown unicast and multicast frames.
>>> This patch adds the necessary DSA infrastructure to allow the Linux
>>> bridge support to control these properties for DSA switches.
>>>
>>> We implement this by providing two new methods: one to get the switch-
>>> wide support bitmask, and another to set the properties.
>>>
>>> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
>>> ---
>>
>> [snip]
>>
>>>  
>>> +int dsa_port_bridge_flags(const struct dsa_port *dp, unsigned long flags,
>>> +			  struct switchdev_trans *trans)
>>> +{
>>> +	struct dsa_switch *ds = dp->ds;
>>> +	int port = dp->index;
>>> +
>>> +	if (switchdev_trans_ph_prepare(trans))
>>> +		return ds->ops->port_bridge_flags ? 0 : -EOPNOTSUPP;
>>> +
>>> +	if (ds->ops->port_bridge_flags)
>>> +		ds->ops->port_bridge_flags(ds, port, flags);
>>
>> If you have a switch fabric with multiple switches, it seems to me that
>> you also need to make sure that the DSA and CPU ports will have
>> compatible flooding attribute, so just like the port_vlan_add()
>> callback, you probably need to make this a switch fabric-wide event and
>> use a notifier here. At least the DSA ports need to have MC flooding
>> turned on for an user port to also have MC flooding working.
> 
> mv88e6xxx already today detects CPU and DSA ports and sets unicast
> and multicast flooding for these ports - see
> mv88e6xxx_setup_egress_floods():

Indeed, probably for historical reasons, since that type of logic should
ideally be migrated to the core DSA layer, this is fine for now though.

> 
>         /* Upstream ports flood frames with unknown unicast or multicast DA */
>         flood = dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port);
>         if (chip->info->ops->port_set_egress_floods)
>                 return chip->info->ops->port_set_egress_floods(chip, port,
>                                                                flood, flood);
> 

-- 
Florian