Subject: [net-next PATCH 1/4] drivers: net: dsa: qca8k: drop MTU tracking from qca8k_priv

From: Ansuel Smith <[email-masked]>
Date: Tue, 22 Mar 2022 02:45:03 +0100

Drop the MTU array from qca8k_priv and use slave net dev to get the max
MTU across all user port. CPU port can be skipped as DSA already make
sure CPU port are set to the max MTU across all ports.

Signed-off-by: Ansuel Smith <[email-masked]>
---
 drivers/net/dsa/qca8k.c | 38 +++++++++++++++++++++++---------------
 drivers/net/dsa/qca8k.h |  1 -
 2 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index d3ed0a7f8077..4366d87b4bbd 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -2367,13 +2367,31 @@ static int
 qca8k_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 {
 	struct qca8k_priv *priv = ds->priv;
-	int i, mtu = 0;
+	struct dsa_port *dp;
+	int mtu = new_mtu;
 
-	priv->port_mtu[port] = new_mtu;
+	/* We have only have a general MTU setting. So check
+	 * every port and set the max across all port.
+	 */
+	list_for_each_entry(dp, &ds->dst->ports, list) {
+		/* We can ignore cpu port, DSA will itself chose
+		 * the max MTU across all port
+		 */
+		if (!dsa_port_is_user(dp))
+			continue;
 
-	for (i = 0; i < QCA8K_NUM_PORTS; i++)
-		if (priv->port_mtu[i] > mtu)
-			mtu = priv->port_mtu[i];
+		if (dp->index == port)
+			continue;
+
+		/* Address init phase where not every port have
+		 * a slave device
+		 */
+		if (!dp->slave)
+			continue;
+
+		if (mtu < dp->slave->mtu)
+			mtu = dp->slave->mtu;
+	}
 
 	/* Include L2 header / FCS length */
 	return qca8k_write(priv, QCA8K_MAX_FRAME_SIZE, mtu + ETH_HLEN + ETH_FCS_LEN);
@@ -3033,16 +3051,6 @@ qca8k_setup(struct dsa_switch *ds)
 				  QCA8K_PORT_HOL_CTRL1_WRED_EN,
 				  mask);
 		}
-
-		/* Set initial MTU for every port.
-		 * We have only have a general MTU setting. So track
-		 * every port and set the max across all port.
-		 * Set per port MTU to 1500 as the MTU change function
-		 * will add the overhead and if its set to 1518 then it
-		 * will apply the overhead again and we will end up with
-		 * MTU of 1536 instead of 1518
-		 */
-		priv->port_mtu[i] = ETH_DATA_LEN;
 	}
 
 	/* Special GLOBAL_FC_THRESH value are needed for ar8327 switch */
diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
index f375627174c8..562d75997e55 100644
--- a/drivers/net/dsa/qca8k.h
+++ b/drivers/net/dsa/qca8k.h
@@ -398,7 +398,6 @@ struct qca8k_priv {
 	struct device *dev;
 	struct dsa_switch_ops ops;
 	struct gpio_desc *reset_gpio;
-	unsigned int port_mtu[QCA8K_NUM_PORTS];
 	struct net_device *mgmt_master; /* Track if mdio/mib Ethernet is available */
 	struct qca8k_mgmt_eth_data mgmt_eth_data;
 	struct qca8k_mib_eth_data mib_eth_data;
-- 
2.34.1