Re: [PATCH] net: dsa: read mac address from DT for slave device

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On 2019-02-27 10:04, xiaofeis@xxxxxxxxxxxxxx wrote:
On 2019-02-26 15:45, xiaofeis@xxxxxxxxxxxxxx wrote:
On 2019-02-26 01:27, Florian Fainelli wrote:
On 2/25/19 5:28 AM, xiaofeis@xxxxxxxxxxxxxx wrote:
Hi Florian

We have two slave DSA interfaces, wan0 and lan0, one is for wan port, and the other is for lan port. Customer has it's mac address pool, they
want
to assign the mac address from the pool on wan0, lan0, and other
interfaces like
wifi, bt. Coreboot/uboot will populate it to the DTS node, so the driver
can
get it from it's node. For DSA slave interface, it already has it's own
DTS node, it's
easy to just add one porperty "local-mac-address" there for the usage in
DSA driver.

If not use DSA framework, normally we will use eth0.x and eth0.y for wan
and lan.
On this case, customer usually also assign the MAC address on these
logical interface
from it's pool.

OK, but this is not necessary per my previous explanation: the CPU <=> WAN pipe is a separate broadcast domain (otherwise it is a security hole since you exposing LAN machines to the outside world), and so there is no need for a separate MAC address. It might be convenient to have one,
especially for the provider, if they run a management software (e.g.:
TR69), but it is not required per-se.

Let me ask a secondary question here, how many Ethernet MACs connect to
the switch in this configuration? Is there one that is supposed to be
assigned all LAN traffic and one that is supposed to be assigned all WAN
traffic? If so, then what you are doing makes even less


Only one MAC connected to switch cpu port, both lan0 and wan0 are on the top of
same interface(eth0).

Customer doesn't care about the MAC controller's MAC address, just
leave it as the driver
randomly generated. They just want to assign the MAC address on wan
and lan DSA logical
interface.

Many customer doesn't use DSA, for example, they use eth0.1/eth0.2 for
lan/wan with one MAC controller.
They configure switch wan port in vlan2 group, and lan port in vlan1
group, they usually assign mac address
on the logical interface(eth0.1&eth0.2), i think this is similar with
DSA slave interfaces.


Unlike vlan logical interface, dsa port already has it's dts node, so it's
easy and natural to add the mac address property for DSA driver use.

On DSA configuration, we won't assign ip on mater eth0. The mac DA from wan port will be the wan0's mac address, the mac DA from lan port will be the lan0's mac address, they are
separate. I think the this is in general on some customer's deploy.


On 2019-02-22 23:43, Florian Fainelli wrote:
On 2/22/19 4:58 AM, Vinod Koul wrote:
From: Xiaofei Shen <xiaofeis@xxxxxxxxxxxxxx>

Before creating a slave netdevice, get the mac address from DTS and
apply in case it is valid.

Can you explain your use case in details?

Assigning a MAC address to a network device that represents a switch port does not quite make sense in general. The switch port is really representing one end of a pipe, so one side you have stations and on the other side, you have the CPU/management Ethernet MAC controller's MAC
address which constitutes a station as well. The DSA slave network
devices are just software constructs meant to steer traffic towards
specific ports of the switch, but they are all from the perpsective of traffic reaching the CPU Port in the first place, therefore traffic that is generally a known unicast Ethernet frame with the CPU's MAC address as MAC DA (and of course all types of unknown MC, management traffic
etc.)

By default, DSA switch need to come up in a configuration where all
ports (except CPU/management) must be strictly separate from every other port such that we can achieve what a standalone Ethernet NIC would do. This works because all ports are isolated from one another, so there is no cross talk and so having the same MAC address (the one from the CPU) on the DSA slave network devices just works, each port is a separate
broadcast domain.

Once you start bridging one or ore ports, the bridge root port will have a MAC address, most likely the one the CPU/management Ethernet MAC, but similarly, this is not an issue and that's exactly how a software bridge
would work as well.


Signed-off-by: Xiaofei Shen <xiaofeis@xxxxxxxxxxxxxx>
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
---
 include/net/dsa.h | 1 +
 net/dsa/dsa2.c    | 1 +
 net/dsa/slave.c   | 5 ++++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index b3eefe8e18fd..aa24ce756679 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -198,6 +198,7 @@ struct dsa_port {
     unsigned int        index;
     const char        *name;
     const struct dsa_port    *cpu_dp;
+    const char        *mac;
     struct device_node    *dn;
     unsigned int        ageing_time;
     u8            stp_state;
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index a1917025e155..afb7d9fa42f6 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -261,6 +261,7 @@ static int dsa_port_setup(struct dsa_port *dp)
     int err = 0;

     memset(&dp->devlink_port, 0, sizeof(dp->devlink_port));
+    dp->mac = of_get_mac_address(dp->dn);

     if (dp->type != DSA_PORT_TYPE_UNUSED)
         err = devlink_port_register(ds->devlink, &dp->devlink_port,
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index a3fcc1d01615..8e64c4e947c6 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1308,7 +1308,10 @@ int dsa_slave_create(struct dsa_port *port)
     slave_dev->features = master->vlan_features | NETIF_F_HW_TC;
     slave_dev->hw_features |= NETIF_F_HW_TC;
     slave_dev->ethtool_ops = &dsa_slave_ethtool_ops;
-    eth_hw_addr_inherit(slave_dev, master);
+    if (port->mac && is_valid_ether_addr(port->mac))
+        ether_addr_copy(slave_dev->dev_addr, port->mac);
+    else
+        eth_hw_addr_inherit(slave_dev, master);
     slave_dev->priv_flags |= IFF_NO_QUEUE;
     slave_dev->netdev_ops = &dsa_slave_netdev_ops;
     slave_dev->switchdev_ops = &dsa_slave_switchdev_ops;




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