netdev - [PATCH v3 2/3] net: mscc: ocelot: split xmit into FDMA and register injection paths

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Message-Id: <20260208225602.1339325-3-n7l8m4@u.northwestern.edu>
Date: Sun,  8 Feb 2026 22:56:01 +0000
From: Ziyi Guo <n7l8m4@...orthwestern.edu>
To: Vladimir Oltean <vladimir.oltean@....com>,
	Claudiu Manoil <claudiu.manoil@....com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: UNGLinuxDriver@...rochip.com,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ziyi Guo <n7l8m4@...orthwestern.edu>
Subject: [PATCH v3 2/3] net: mscc: ocelot: split xmit into FDMA and register injection paths

Split ocelot_port_xmit() into two separate functions:
- ocelot_port_xmit_fdma(): handles the FDMA injection path
- ocelot_port_xmit_inj(): handles the register-based injection path

The top-level ocelot_port_xmit() now dispatches to the appropriate
function based on the ocelot_fdma_enabled static key.

This is a pure refactor with no behavioral change. Separating the two
code paths makes each one simpler and prepares for adding proper locking
to the register injection path without affecting the FDMA path.

Signed-off-by: Ziyi Guo <n7l8m4@...orthwestern.edu>
---
 drivers/net/ethernet/mscc/ocelot_net.c | 39 ++++++++++++++++++++------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c
index ef4a6c768de9..d6b0936beca2 100644
--- a/drivers/net/ethernet/mscc/ocelot_net.c
+++ b/drivers/net/ethernet/mscc/ocelot_net.c
@@ -571,7 +571,25 @@ static bool ocelot_xmit_timestamp(struct ocelot *ocelot, int port,
 	return true;
 }
 
-static netdev_tx_t ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ocelot_port_xmit_fdma(struct sk_buff *skb,
+					 struct net_device *dev)
+{
+	struct ocelot_port_private *priv = netdev_priv(dev);
+	struct ocelot_port *ocelot_port = &priv->port;
+	struct ocelot *ocelot = ocelot_port->ocelot;
+	int port = priv->port.index;
+	u32 rew_op = 0;
+
+	if (!ocelot_xmit_timestamp(ocelot, port, skb, &rew_op))
+		return NETDEV_TX_OK;
+
+	ocelot_fdma_inject_frame(ocelot, port, rew_op, skb, dev);
+
+	return NETDEV_TX_OK;
+}
+
+static netdev_tx_t ocelot_port_xmit_inj(struct sk_buff *skb,
+					struct net_device *dev)
 {
 	struct ocelot_port_private *priv = netdev_priv(dev);
 	struct ocelot_port *ocelot_port = &priv->port;
@@ -579,24 +597,27 @@ static netdev_tx_t ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev)
 	int port = priv->port.index;
 	u32 rew_op = 0;
 
-	if (!static_branch_unlikely(&ocelot_fdma_enabled) &&
-	    !ocelot_can_inject(ocelot, 0))
+	if (!ocelot_can_inject(ocelot, 0))
 		return NETDEV_TX_BUSY;
 
 	if (!ocelot_xmit_timestamp(ocelot, port, skb, &rew_op))
 		return NETDEV_TX_OK;
 
-	if (static_branch_unlikely(&ocelot_fdma_enabled)) {
-		ocelot_fdma_inject_frame(ocelot, port, rew_op, skb, dev);
-	} else {
-		ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
+	ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb);
 
-		consume_skb(skb);
-	}
+	consume_skb(skb);
 
 	return NETDEV_TX_OK;
 }
 
+static netdev_tx_t ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	if (static_branch_unlikely(&ocelot_fdma_enabled))
+		return ocelot_port_xmit_fdma(skb, dev);
+
+	return ocelot_port_xmit_inj(skb, dev);
+}
+
 enum ocelot_action_type {
 	OCELOT_MACT_LEARN,
 	OCELOT_MACT_FORGET,
-- 
2.34.1