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Message-Id: <20251124-k1-ethernet-actually-remove-fc-v2-1-5e77ab69b791@iscas.ac.cn>
Date: Mon, 24 Nov 2025 13:28:27 +0800
From: Vivian Wang <wangruikang@...as.ac.cn>
To: 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>, 
 Yixun Lan <dlan@...too.org>, Vadim Fedorenko <vadim.fedorenko@...ux.dev>, 
 Troy Mitchell <troy.mitchell@...ux.spacemit.com>, 
 Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc: netdev@...r.kernel.org, linux-riscv@...ts.infradead.org, 
 spacemit@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 Vivian Wang <wangruikang@...as.ac.cn>
Subject: [PATCH net-next v2] net: spacemit: Remove broken flow control
 support

The current flow control implementation doesn't handle autonegotiation
and ethtool operations properly. Remove it for now so we don't claim
support for something that doesn't really work. A better implementation
will be sent in future patches.

Fixes: bfec6d7f2001 ("net: spacemit: Add K1 Ethernet MAC")
Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>
---
Starting at v2 as this is the net-next successor of:

  https://lore.kernel.org/spacemit/20251031-k1-ethernet-remove-fc-v1-1-1ae3f1d6508c@iscas.ac.cn/
---
 drivers/net/ethernet/spacemit/k1_emac.c | 110 --------------------------------
 1 file changed, 110 deletions(-)

diff --git a/drivers/net/ethernet/spacemit/k1_emac.c b/drivers/net/ethernet/spacemit/k1_emac.c
index 220eb5ce7583..c85dc742c404 100644
--- a/drivers/net/ethernet/spacemit/k1_emac.c
+++ b/drivers/net/ethernet/spacemit/k1_emac.c
@@ -46,8 +46,6 @@
 #define EMAC_RX_FRAMES			64
 #define EMAC_RX_COAL_TIMEOUT		(600 * 312)
 
-#define DEFAULT_FC_PAUSE_TIME		0xffff
-#define DEFAULT_FC_FIFO_HIGH		1600
 #define DEFAULT_TX_ALMOST_FULL		0x1f8
 #define DEFAULT_TX_THRESHOLD		1518
 #define DEFAULT_RX_THRESHOLD		12
@@ -132,9 +130,6 @@ struct emac_priv {
 	u32 tx_delay;
 	u32 rx_delay;
 
-	bool flow_control_autoneg;
-	u8 flow_control;
-
 	/* Softirq-safe, hold while touching hardware statistics */
 	spinlock_t stats_lock;
 };
@@ -179,9 +174,7 @@ static void emac_set_mac_addr_reg(struct emac_priv *priv,
 
 static void emac_set_mac_addr(struct emac_priv *priv, const unsigned char *addr)
 {
-	/* We use only one address, so set the same for flow control as well */
 	emac_set_mac_addr_reg(priv, addr, MAC_ADDRESS1_HIGH);
-	emac_set_mac_addr_reg(priv, addr, MAC_FC_SOURCE_ADDRESS_HIGH);
 }
 
 static void emac_reset_hw(struct emac_priv *priv)
@@ -200,9 +193,6 @@ static void emac_reset_hw(struct emac_priv *priv)
 
 static void emac_init_hw(struct emac_priv *priv)
 {
-	/* Destination address for 802.3x Ethernet flow control */
-	u8 fc_dest_addr[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x01 };
-
 	u32 rxirq = 0, dma = 0;
 
 	regmap_set_bits(priv->regmap_apmu,
@@ -228,12 +218,6 @@ static void emac_init_hw(struct emac_priv *priv)
 		DEFAULT_TX_THRESHOLD);
 	emac_wr(priv, MAC_RECEIVE_PACKET_START_THRESHOLD, DEFAULT_RX_THRESHOLD);
 
-	/* Configure flow control (enabled in emac_adjust_link() later) */
-	emac_set_mac_addr_reg(priv, fc_dest_addr, MAC_FC_SOURCE_ADDRESS_HIGH);
-	emac_wr(priv, MAC_FC_PAUSE_HIGH_THRESHOLD, DEFAULT_FC_FIFO_HIGH);
-	emac_wr(priv, MAC_FC_HIGH_PAUSE_TIME, DEFAULT_FC_PAUSE_TIME);
-	emac_wr(priv, MAC_FC_PAUSE_LOW_THRESHOLD, 0);
-
 	/* RX IRQ mitigation */
 	rxirq = FIELD_PREP(MREGBIT_RECEIVE_IRQ_FRAME_COUNTER_MASK,
 			   EMAC_RX_FRAMES);
@@ -1018,57 +1002,6 @@ static int emac_mdio_init(struct emac_priv *priv)
 	return ret;
 }
 
-static void emac_set_tx_fc(struct emac_priv *priv, bool enable)
-{
-	u32 val;
-
-	val = emac_rd(priv, MAC_FC_CONTROL);
-
-	FIELD_MODIFY(MREGBIT_FC_GENERATION_ENABLE, &val, enable);
-	FIELD_MODIFY(MREGBIT_AUTO_FC_GENERATION_ENABLE, &val, enable);
-
-	emac_wr(priv, MAC_FC_CONTROL, val);
-}
-
-static void emac_set_rx_fc(struct emac_priv *priv, bool enable)
-{
-	u32 val = emac_rd(priv, MAC_FC_CONTROL);
-
-	FIELD_MODIFY(MREGBIT_FC_DECODE_ENABLE, &val, enable);
-
-	emac_wr(priv, MAC_FC_CONTROL, val);
-}
-
-static void emac_set_fc(struct emac_priv *priv, u8 fc)
-{
-	emac_set_tx_fc(priv, fc & FLOW_CTRL_TX);
-	emac_set_rx_fc(priv, fc & FLOW_CTRL_RX);
-	priv->flow_control = fc;
-}
-
-static void emac_set_fc_autoneg(struct emac_priv *priv)
-{
-	struct phy_device *phydev = priv->ndev->phydev;
-	u32 local_adv, remote_adv;
-	u8 fc;
-
-	local_adv = linkmode_adv_to_lcl_adv_t(phydev->advertising);
-
-	remote_adv = 0;
-
-	if (phydev->pause)
-		remote_adv |= LPA_PAUSE_CAP;
-
-	if (phydev->asym_pause)
-		remote_adv |= LPA_PAUSE_ASYM;
-
-	fc = mii_resolve_flowctrl_fdx(local_adv, remote_adv);
-
-	priv->flow_control_autoneg = true;
-
-	emac_set_fc(priv, fc);
-}
-
 /*
  * Even though this MAC supports gigabit operation, it only provides 32-bit
  * statistics counters. The most overflow-prone counters are the "bytes" ones,
@@ -1425,42 +1358,6 @@ static void emac_ethtool_get_regs(struct net_device *dev,
 			emac_rd(priv, MAC_GLOBAL_CONTROL + i * 4);
 }
 
-static void emac_get_pauseparam(struct net_device *dev,
-				struct ethtool_pauseparam *pause)
-{
-	struct emac_priv *priv = netdev_priv(dev);
-
-	pause->autoneg = priv->flow_control_autoneg;
-	pause->tx_pause = !!(priv->flow_control & FLOW_CTRL_TX);
-	pause->rx_pause = !!(priv->flow_control & FLOW_CTRL_RX);
-}
-
-static int emac_set_pauseparam(struct net_device *dev,
-			       struct ethtool_pauseparam *pause)
-{
-	struct emac_priv *priv = netdev_priv(dev);
-	u8 fc = 0;
-
-	if (!netif_running(dev))
-		return -ENETDOWN;
-
-	priv->flow_control_autoneg = pause->autoneg;
-
-	if (pause->autoneg) {
-		emac_set_fc_autoneg(priv);
-	} else {
-		if (pause->tx_pause)
-			fc |= FLOW_CTRL_TX;
-
-		if (pause->rx_pause)
-			fc |= FLOW_CTRL_RX;
-
-		emac_set_fc(priv, fc);
-	}
-
-	return 0;
-}
-
 static void emac_get_drvinfo(struct net_device *dev,
 			     struct ethtool_drvinfo *info)
 {
@@ -1634,8 +1531,6 @@ static void emac_adjust_link(struct net_device *dev)
 		}
 
 		emac_wr(priv, MAC_GLOBAL_CONTROL, ctrl);
-
-		emac_set_fc_autoneg(priv);
 	}
 
 	phy_print_status(phydev);
@@ -1715,8 +1610,6 @@ static int emac_phy_connect(struct net_device *ndev)
 		goto err_node_put;
 	}
 
-	phy_support_asym_pause(phydev);
-
 	phydev->mac_managed_pm = true;
 
 	emac_update_delay_line(priv);
@@ -1886,9 +1779,6 @@ static const struct ethtool_ops emac_ethtool_ops = {
 	.get_sset_count		= emac_get_sset_count,
 	.get_strings		= emac_get_strings,
 	.get_ethtool_stats	= emac_get_ethtool_stats,
-
-	.get_pauseparam		= emac_get_pauseparam,
-	.set_pauseparam		= emac_set_pauseparam,
 };
 
 static const struct net_device_ops emac_netdev_ops = {

---
base-commit: 6a23ae0a96a600d1d12557add110e0bb6e32730c
change-id: 20251124-k1-ethernet-actually-remove-fc-706831770489

Best regards,
-- 
Vivian "dramforever" Wang


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