[PATCH net-next 05/12] net: dsa: qca8k: Move request sequence number... | netdev

[PATCH net-next 05/12] net: dsa: qca8k: Move request sequence number handling into core

From: Luke Howard <hidden>
Date: 2026-07-03 07:30:59
Also in: lkml
Subsystem: networking drivers, networking [dsa], networking [general], the rest · Maintainers: Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Vladimir Oltean, Linus Torvalds

From: Andrew Lunn <andrew@lunn.ch>

Each request/reply frame is likely to have a sequence number so that
request and the reply can be matched together. Move this sequence
number into the inband structure. The driver must provide a helper to
insert the sequence number into the skb, and the core will perform the
increment.

To allow different devices to have different size sequence numbers, a
mask is provided. This can be used for example to reduce the u32
sequence number down to a u8.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/dsa/qca/qca8k-8xxx.c | 29 +++++++++--------------------
 drivers/net/dsa/qca/qca8k.h      |  1 -
 include/net/dsa.h                |  6 +++++-
 net/dsa/dsa.c                    | 16 +++++++++++++++-
 4 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
index 3b3fe96016176..fc5070402188e 100644
--- a/drivers/net/dsa/qca/qca8k-8xxx.c
+++ b/drivers/net/dsa/qca/qca8k-8xxx.c

@@ -186,7 +186,8 @@ static void qca8k_rw_reg_ack_handler(struct dsa_switch *ds, struct sk_buff *skb)
 	len *= sizeof(u16);
 
 	/* Make sure the seq match the requested packet. If not, drop. */
-	if (get_unaligned_le32(&mgmt_ethhdr->seq) != mgmt_eth_data->seq)
+	if (get_unaligned_le32(&mgmt_ethhdr->seq) !=
+	    dsa_inband_seqno(&mgmt_eth_data->inband))
 		return;
 
 	if (cmd == MDIO_READ) {

@@ -332,12 +333,10 @@ static int qca8k_read_eth(struct qca8k_priv *priv, u32 reg, u32 *val, int len)
 
 	skb->dev = priv->mgmt_conduit;
 
-	/* Increment seq_num and set it in the mdio pkt */
-	mgmt_eth_data->seq++;
-	qca8k_mdio_header_fill_seq_num(skb, mgmt_eth_data->seq);
 	mgmt_eth_data->ack = false;
 
 	ret = dsa_inband_request(&mgmt_eth_data->inband, skb,
+				 qca8k_mdio_header_fill_seq_num,
 				 QCA8K_ETHERNET_TIMEOUT);
 
 	*val = mgmt_eth_data->data[0];

@@ -380,12 +379,10 @@ static int qca8k_write_eth(struct qca8k_priv *priv, u32 reg, u32 *val, int len)
 
 	skb->dev = priv->mgmt_conduit;
 
-	/* Increment seq_num and set it in the mdio pkt */
-	mgmt_eth_data->seq++;
-	qca8k_mdio_header_fill_seq_num(skb, mgmt_eth_data->seq);
 	mgmt_eth_data->ack = false;
 
 	ret = dsa_inband_request(&mgmt_eth_data->inband, skb,
+				 qca8k_mdio_header_fill_seq_num,
 				 QCA8K_ETHERNET_TIMEOUT);
 
 	ack = mgmt_eth_data->ack;

@@ -586,12 +583,10 @@ qca8k_phy_eth_busy_wait(struct qca8k_mgmt_eth_data *mgmt_eth_data,
 	if (!skb)
 		return -ENOMEM;
 
-	/* Increment seq_num and set it in the copy pkt */
-	mgmt_eth_data->seq++;
-	qca8k_mdio_header_fill_seq_num(skb, mgmt_eth_data->seq);
 	mgmt_eth_data->ack = false;
 
 	ret = dsa_inband_request(&mgmt_eth_data->inband, skb,
+				 qca8k_mdio_header_fill_seq_num,
 				 QCA8K_ETHERNET_TIMEOUT);
 
 	ack = mgmt_eth_data->ack;

@@ -684,12 +679,10 @@ qca8k_phy_eth_command(struct qca8k_priv *priv, bool read, int phy,
 	clear_skb->dev = mgmt_conduit;
 	write_skb->dev = mgmt_conduit;
 
-	/* Increment seq_num and set it in the write pkt */
-	mgmt_eth_data->seq++;
-	qca8k_mdio_header_fill_seq_num(write_skb, mgmt_eth_data->seq);
 	mgmt_eth_data->ack = false;
 
 	ret = dsa_inband_request(&mgmt_eth_data->inband, write_skb,
+				 qca8k_mdio_header_fill_seq_num,
 				 QCA8K_ETHERNET_TIMEOUT);
 
 	ack = mgmt_eth_data->ack;

@@ -716,12 +709,10 @@ qca8k_phy_eth_command(struct qca8k_priv *priv, bool read, int phy,
 	}
 
 	if (read) {
-		/* Increment seq_num and set it in the read pkt */
-		mgmt_eth_data->seq++;
-		qca8k_mdio_header_fill_seq_num(read_skb, mgmt_eth_data->seq);
 		mgmt_eth_data->ack = false;
 
 		ret = dsa_inband_request(&mgmt_eth_data->inband, read_skb,
+					 qca8k_mdio_header_fill_seq_num,
 					 QCA8K_ETHERNET_TIMEOUT);
 
 		ack = mgmt_eth_data->ack;

@@ -739,13 +730,11 @@ qca8k_phy_eth_command(struct qca8k_priv *priv, bool read, int phy,
 		kfree_skb(read_skb);
 	}
 exit:
-	/* Increment seq_num and set it in the clear pkt */
-	mgmt_eth_data->seq++;
-	qca8k_mdio_header_fill_seq_num(clear_skb, mgmt_eth_data->seq);
 	mgmt_eth_data->ack = false;
 
 	/* This is expected to fail sometimes, so don't check return value. */
 	dsa_inband_request(&mgmt_eth_data->inband, clear_skb,
+			   qca8k_mdio_header_fill_seq_num,
 			   QCA8K_ETHERNET_TIMEOUT);
 
 	mutex_unlock(&mgmt_eth_data->mutex);

@@ -2080,7 +2069,7 @@ qca8k_sw_probe(struct mdio_device *mdiodev)
 		return -ENOMEM;
 
 	mutex_init(&priv->mgmt_eth_data.mutex);
-	dsa_inband_init(&priv->mgmt_eth_data.inband);
+	dsa_inband_init(&priv->mgmt_eth_data.inband, U32_MAX);
 
 	mutex_init(&priv->mib_eth_data.mutex);
 	init_completion(&priv->mib_eth_data.rw_done);

diff --git a/drivers/net/dsa/qca/qca8k.h b/drivers/net/dsa/qca/qca8k.h
index 938f2c9ff0cac..1054ba1c7e590 100644
--- a/drivers/net/dsa/qca/qca8k.h
+++ b/drivers/net/dsa/qca/qca8k.h

@@ -395,7 +395,6 @@ struct qca8k_mgmt_eth_data {
 	struct dsa_inband inband;
 	struct mutex mutex; /* Enforce one mdio read/write at time */
 	bool ack;
-	u32 seq;
 	u32 data[4];
 };

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 6b5aeb99ec3bb..cdf2487397c2b 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h

@@ -1353,13 +1353,17 @@ int dsa_port_simple_hsr_leave(struct dsa_switch *ds, int port,
  */
 struct dsa_inband {
 	struct completion completion;
+	u32 seqno;
+	u32 seqno_mask;
 };
 
-void dsa_inband_init(struct dsa_inband *inband);
+void dsa_inband_init(struct dsa_inband *inband, u32 seqno_mask);
 void dsa_inband_complete(struct dsa_inband *inband);
 int dsa_inband_request(struct dsa_inband *inband, struct sk_buff *skb,
+		       void (*insert_seqno)(struct sk_buff *skb, u32 seqno),
 		       int timeout_ms);
 int dsa_inband_wait_for_completion(struct dsa_inband *inband, int timeout_ms);
+u32 dsa_inband_seqno(struct dsa_inband *inband);
 
 /* Keep inline for faster access in hot path */
 static inline bool netdev_uses_dsa(const struct net_device *dev)

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index f6ae11b06b4ab..98a75ee08f011 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c

@@ -1834,9 +1834,11 @@ int dsa_port_simple_hsr_leave(struct dsa_switch *ds, int port,
 }
 EXPORT_SYMBOL_GPL(dsa_port_simple_hsr_leave);
 
-void dsa_inband_init(struct dsa_inband *inband)
+void dsa_inband_init(struct dsa_inband *inband, u32 seqno_mask)
 {
 	init_completion(&inband->completion);
+	inband->seqno_mask = seqno_mask;
+	inband->seqno = 0;
 }
 EXPORT_SYMBOL_GPL(dsa_inband_init);

@@ -1875,11 +1877,17 @@ EXPORT_SYMBOL_GPL(dsa_inband_wait_for_completion);
  * be reinitialised before the skb is queued, to avoid races.
  */
 int dsa_inband_request(struct dsa_inband *inband, struct sk_buff *skb,
+		       void (*insert_seqno)(struct sk_buff *skb, u32 seqno),
 		       int timeout_ms)
 {
 	unsigned long jiffies = msecs_to_jiffies(timeout_ms);
 	int ret;
 
+	if (insert_seqno) {
+		WRITE_ONCE(inband->seqno, inband->seqno + 1);
+		insert_seqno(skb, inband->seqno & inband->seqno_mask);
+	}
+
 	reinit_completion(&inband->completion);
 
 	dev_queue_xmit(skb);

@@ -1891,6 +1899,12 @@ int dsa_inband_request(struct dsa_inband *inband, struct sk_buff *skb,
 }
 EXPORT_SYMBOL_GPL(dsa_inband_request);
 
+u32 dsa_inband_seqno(struct dsa_inband *inband)
+{
+	return READ_ONCE(inband->seqno) & inband->seqno_mask;
+}
+EXPORT_SYMBOL_GPL(dsa_inband_seqno);
+
 static const struct dsa_stubs __dsa_stubs = {
 	.conduit_hwtstamp_validate = __dsa_conduit_hwtstamp_validate,
 };

-- 
2.43.0

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