[PATCH net] net: dsa: sja1105: fix address learning getting disabled on the CPU port

[PATCH net] net: dsa: sja1105: fix address learning getting disabled on the CPU port

[Vladimir Oltean]

In May 2019 when commit 640f763f98c2 ("net: dsa: sja1105: Add support
for Spanning Tree Protocol") was introduced, the comment that "STP does
not get called for the CPU port" was true. This changed after commit
0394a63acfe2 ("net: dsa: enable and disable all ports") in August 2019
and went largely unnoticed, because the sja1105_bridge_stp_state_set()
method did nothing different compared to the static setup done by
sja1105_init_mac_settings().

With the ability to turn address learning off introduced by the blamed
commit, there is a new priv->learn_ena port mask in the driver. When
sja1105_bridge_stp_state_set() gets called and we are in
BR_STATE_LEARNING or later, address learning is enabled or not depending
on priv->learn_ena & BIT(port).

So what happens is that priv->learn_ena is not being set from anywhere
for the CPU port, and the static configuration done by
sja1105_init_mac_settings() is being overwritten.

To solve this, acknowledge that the static configuration of STP state is
no longer necessary because the STP state is being set by the DSA core
now, but what is necessary is to set priv->learn_ena for the CPU port.

Fixes: 4d9423549501 ("net: dsa: sja1105: offload bridge port flags to device")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/dsa/sja1105/sja1105_main.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 4f0545605f6b..ced8c9cb29c2 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -122,14 +122,12 @@ static int sja1105_init_mac_settings(struct sja1105_private *priv)
 
 	for (i = 0; i < ds->num_ports; i++) {
 		mac[i] = default_mac;
-		if (i == dsa_upstream_port(priv->ds, i)) {
-			/* STP doesn't get called for CPU port, so we need to
-			 * set the I/O parameters statically.
-			 */
-			mac[i].dyn_learn = true;
-			mac[i].ingress = true;
-			mac[i].egress = true;
-		}
+
+		/* Let sja1105_bridge_stp_state_set() keep address learning
+		 * enabled for the CPU port.
+		 */
+		if (dsa_is_cpu_port(ds, i))
+			priv->learn_ena |= BIT(i);
 	}
 
 	return 0;
-- 
2.25.1

Re: [PATCH net] net: dsa: sja1105: fix address learning getting disabled on the CPU port

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Tue, 13 Jul 2021 12:37:19 +0300 you wrote:
> In May 2019 when commit 640f763f98c2 ("net: dsa: sja1105: Add support
> for Spanning Tree Protocol") was introduced, the comment that "STP does
> not get called for the CPU port" was true. This changed after commit
> 0394a63acfe2 ("net: dsa: enable and disable all ports") in August 2019
> and went largely unnoticed, because the sja1105_bridge_stp_state_set()
> method did nothing different compared to the static setup done by
> sja1105_init_mac_settings().
> 
> [...]

Here is the summary with links:
  - [net] net: dsa: sja1105: fix address learning getting disabled on the CPU port
    https://git.kernel.org/netdev/net/c/b0b33b048dcf

You are awesome, thank you!
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