[PATCH iwl-next v5 0/4] igc: add support for forcing link speed without autonegotiation

[PATCH iwl-next v5 0/4] igc: add support for forcing link speed without autonegotiation

[KhaiWenTan]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

This series adds support for forcing 10/100 Mb/s link speed via ethtool
when autonegotiation is disabled on the igc driver.

Changes in v5:
- add removal justification to include copper context in commit
  description for igc: remove unused autoneg_failed field (Paul)
- check that cmd->base.duplex is either DUPLEX_HALF or DUPLEX_FULL
  in igc_ethtool_set_link_ksettings() (Simon)
- dynamically override hw->fc.current_mode to igc_fc_none during
  link configuration instead of mutating requested_mode (Simon)

Changes in v4:
- Validate that autoneg is AUTONEG_ENABLE or AUTONEG_DISABLE early
  in igc_ethtool_set_link_ksettings() to avoid passing unexpected
  values to igc_handle_autoneg_disabled(). (Simon Horman)

Changes in v3:
- Modify condition from "if (duplex == DUPLEX_HALF)" to
  "if (duplex != DUPLEX_FULL)". (Simon Horman)

Changes in v2:
- When forcing half-duplex, set hw->fc.requested_mode = igc_fc_none,
  since half-duplex cannot support flow control per IEEE 802.3.
  (Simon Horman)
- Split the original single patch into three patches for clarity:
  patches 1 and 2 are preparatory cleanups; patch 3 carries the
  functional change.

v4 at:
https://patchwork.ozlabs.org/project/intel-wired-lan/cover/20260428060009.311393-1-khai.wen.tan@linux.intel.com/

v3 at:
https://patchwork.ozlabs.org/project/intel-wired-lan/cover/20260422155701.7420-1-khai.wen.tan@linux.intel.com/

v2 at:
https://patchwork.kernel.org/project/netdevbpf/patch/20260416015520.6090-4-khai.wen.tan@linux.intel.com/

v1 at:
https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20260409072747.217836-1-khai.wen.tan@linux.intel.com/

Faizal Rahim (4):
  igc: remove unused autoneg_failed field
  igc: move autoneg-enabled settings into igc_handle_autoneg_enabled()
  igc: replace goto out with direct returns in
    igc_config_fc_after_link_up()
  igc: add support for forcing link speed without autonegotiation

 drivers/net/ethernet/intel/igc/igc_base.c    |  35 +++-
 drivers/net/ethernet/intel/igc/igc_defines.h |   9 +-
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 210 +++++++++++++------
 drivers/net/ethernet/intel/igc/igc_hw.h      |  10 +-
 drivers/net/ethernet/intel/igc/igc_mac.c     |  35 ++--
 drivers/net/ethernet/intel/igc/igc_main.c    |   2 +-
 drivers/net/ethernet/intel/igc/igc_phy.c     |  65 +++++-
 drivers/net/ethernet/intel/igc/igc_phy.h     |   1 +
 8 files changed, 268 insertions(+), 99 deletions(-)

--
2.43.0

[PATCH iwl-next v5 1/4] igc: remove unused autoneg_failed field

[KhaiWenTan]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

autoneg_failed in struct igc_mac_info is never set in the igc driver.
Remove the field and the dead code checking it in
igc_config_fc_after_link_up().

The field originates from the e1000/e1000e fiber/serdes forced-link
path, where MAC-level autoneg timeout sets it to signal the flow-control
code to force pause. igc supports only copper, so it never needs to set
this field.

Reviewed-by: Looi Hong Aun <hong.aun.looi@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Khai Wen Tan <khai.wen.tan@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_hw.h  |  1 -
 drivers/net/ethernet/intel/igc/igc_mac.c | 16 +---------------
 2 files changed, 1 insertion(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_hw.h b/drivers/net/ethernet/intel/igc/igc_hw.h
index be8a49a86d09..86ab8f566f44 100644
--- a/drivers/net/ethernet/intel/igc/igc_hw.h
+++ b/drivers/net/ethernet/intel/igc/igc_hw.h
@@ -92,7 +92,6 @@ struct igc_mac_info {
 	bool asf_firmware_present;
 	bool arc_subsystem_valid;
 
-	bool autoneg_failed;
 	bool get_link_status;
 };
 
diff --git a/drivers/net/ethernet/intel/igc/igc_mac.c b/drivers/net/ethernet/intel/igc/igc_mac.c
index 7ac6637f8db7..142beb9ae557 100644
--- a/drivers/net/ethernet/intel/igc/igc_mac.c
+++ b/drivers/net/ethernet/intel/igc/igc_mac.c
@@ -438,28 +438,14 @@ void igc_config_collision_dist(struct igc_hw *hw)
  * Checks the status of auto-negotiation after link up to ensure that the
  * speed and duplex were not forced.  If the link needed to be forced, then
  * flow control needs to be forced also.  If auto-negotiation is enabled
- * and did not fail, then we configure flow control based on our link
- * partner.
+ * then we configure flow control based on our link partner.
  */
 s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 {
 	u16 mii_status_reg, mii_nway_adv_reg, mii_nway_lp_ability_reg;
-	struct igc_mac_info *mac = &hw->mac;
 	u16 speed, duplex;
 	s32 ret_val = 0;
 
-	/* Check for the case where we have fiber media and auto-neg failed
-	 * so we had to force link.  In this case, we need to force the
-	 * configuration of the MAC to match the "fc" parameter.
-	 */
-	if (mac->autoneg_failed)
-		ret_val = igc_force_mac_fc(hw);
-
-	if (ret_val) {
-		hw_dbg("Error forcing flow control settings\n");
-		goto out;
-	}
-
 	/* In auto-neg, we need to check and see if Auto-Neg has completed,
 	 * and if so, how the PHY and link partner has flow control
 	 * configured.
-- 
2.43.0

[PATCH iwl-next v5 2/4] igc: move autoneg-enabled settings into igc_handle_autoneg_enabled()

[KhaiWenTan]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

Move the advertised link modes and flow control configuration from
igc_ethtool_set_link_ksettings() into igc_handle_autoneg_enabled().

No functional change.

Reviewed-by: Looi Hong Aun <hong.aun.looi@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Khai Wen Tan <khai.wen.tan@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 72 ++++++++++++--------
 1 file changed, 44 insertions(+), 28 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index 0122009bedd0..cfcbf2fdad6e 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -2000,6 +2000,49 @@ static int igc_ethtool_get_link_ksettings(struct net_device *netdev,
 	return 0;
 }
 
+/**
+ * igc_handle_autoneg_enabled - Configure autonegotiation advertisement
+ * @adapter: private driver structure
+ * @cmd: ethtool link ksettings from user
+ *
+ * Records advertised speeds and flow control settings when autoneg
+ * is enabled.
+ */
+static void igc_handle_autoneg_enabled(struct igc_adapter *adapter,
+				       const struct ethtool_link_ksettings *cmd)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u16 advertised = 0;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  2500baseT_Full))
+		advertised |= ADVERTISE_2500_FULL;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  1000baseT_Full))
+		advertised |= ADVERTISE_1000_FULL;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  100baseT_Full))
+		advertised |= ADVERTISE_100_FULL;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  100baseT_Half))
+		advertised |= ADVERTISE_100_HALF;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  10baseT_Full))
+		advertised |= ADVERTISE_10_FULL;
+
+	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
+						  10baseT_Half))
+		advertised |= ADVERTISE_10_HALF;
+
+	hw->phy.autoneg_advertised = advertised;
+	if (adapter->fc_autoneg)
+		hw->fc.requested_mode = igc_fc_default;
+}
+
 static int
 igc_ethtool_set_link_ksettings(struct net_device *netdev,
 			       const struct ethtool_link_ksettings *cmd)
@@ -2007,7 +2050,6 @@ igc_ethtool_set_link_ksettings(struct net_device *netdev,
 	struct igc_adapter *adapter = netdev_priv(netdev);
 	struct net_device *dev = adapter->netdev;
 	struct igc_hw *hw = &adapter->hw;
-	u16 advertised = 0;
 
 	/* When adapter in resetting mode, autoneg/speed/duplex
 	 * cannot be changed
@@ -2032,34 +2074,8 @@ igc_ethtool_set_link_ksettings(struct net_device *netdev,
 	while (test_and_set_bit(__IGC_RESETTING, &adapter->state))
 		usleep_range(1000, 2000);
 
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  2500baseT_Full))
-		advertised |= ADVERTISE_2500_FULL;
-
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  1000baseT_Full))
-		advertised |= ADVERTISE_1000_FULL;
-
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  100baseT_Full))
-		advertised |= ADVERTISE_100_FULL;
-
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  100baseT_Half))
-		advertised |= ADVERTISE_100_HALF;
-
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  10baseT_Full))
-		advertised |= ADVERTISE_10_FULL;
-
-	if (ethtool_link_ksettings_test_link_mode(cmd, advertising,
-						  10baseT_Half))
-		advertised |= ADVERTISE_10_HALF;
-
 	if (cmd->base.autoneg == AUTONEG_ENABLE) {
-		hw->phy.autoneg_advertised = advertised;
-		if (adapter->fc_autoneg)
-			hw->fc.requested_mode = igc_fc_default;
+		igc_handle_autoneg_enabled(adapter, cmd);
 	} else {
 		netdev_info(dev, "Force mode currently not supported\n");
 	}
-- 
2.43.0

[PATCH iwl-next v5 3/4] igc: replace goto out with direct returns in igc_config_fc_after_link_up()

[KhaiWenTan]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

The out: label only returns ret_val with no cleanup. The kernel coding
style guide states: "If there is no cleanup needed then just return
directly." (Documentation/process/coding-style.rst, section 7).

This improves readability ahead of a subsequent patch that introduces a
new goto label in this function.

No functional change.

Reviewed-by: Looi Hong Aun <hong.aun.looi@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Khai Wen Tan <khai.wen.tan@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_mac.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_mac.c b/drivers/net/ethernet/intel/igc/igc_mac.c
index 142beb9ae557..0a3d3f357505 100644
--- a/drivers/net/ethernet/intel/igc/igc_mac.c
+++ b/drivers/net/ethernet/intel/igc/igc_mac.c
@@ -458,15 +458,15 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	ret_val = hw->phy.ops.read_reg(hw, PHY_STATUS,
 				       &mii_status_reg);
 	if (ret_val)
-		goto out;
+		return ret_val;
 	ret_val = hw->phy.ops.read_reg(hw, PHY_STATUS,
 				       &mii_status_reg);
 	if (ret_val)
-		goto out;
+		return ret_val;
 
 	if (!(mii_status_reg & MII_SR_AUTONEG_COMPLETE)) {
 		hw_dbg("Copper PHY and Auto Neg has not completed.\n");
-		goto out;
+		return ret_val;
 	}
 
 	/* The AutoNeg process has completed, so we now need to
@@ -478,11 +478,11 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	ret_val = hw->phy.ops.read_reg(hw, PHY_AUTONEG_ADV,
 				       &mii_nway_adv_reg);
 	if (ret_val)
-		goto out;
+		return ret_val;
 	ret_val = hw->phy.ops.read_reg(hw, PHY_LP_ABILITY,
 				       &mii_nway_lp_ability_reg);
 	if (ret_val)
-		goto out;
+		return ret_val;
 	/* Two bits in the Auto Negotiation Advertisement Register
 	 * (Address 4) and two bits in the Auto Negotiation Base
 	 * Page Ability Register (Address 5) determine flow control
@@ -598,7 +598,7 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	ret_val = hw->mac.ops.get_speed_and_duplex(hw, &speed, &duplex);
 	if (ret_val) {
 		hw_dbg("Error getting link speed and duplex\n");
-		goto out;
+		return ret_val;
 	}
 
 	if (duplex == HALF_DUPLEX)
@@ -610,10 +610,9 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	ret_val = igc_force_mac_fc(hw);
 	if (ret_val) {
 		hw_dbg("Error forcing flow control settings\n");
-		goto out;
+		return ret_val;
 	}
 
-out:
 	return ret_val;
 }
 
-- 
2.43.0

[PATCH iwl-next v5 4/4] igc: add support for forcing link speed without autonegotiation

[KhaiWenTan]

From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>

Allow users to force 10/100 Mb/s link speed and duplex via ethtool
when autonegotiation is disabled. Previously, the driver rejected
these requests with "Force mode currently not supported.".

Forcing at 1000 Mb/s and 2500 Mb/s is not supported.

Reviewed-by: Looi Hong Aun <hong.aun.looi@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
Signed-off-by: Khai Wen Tan <khai.wen.tan@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_base.c    |  35 ++++-
 drivers/net/ethernet/intel/igc/igc_defines.h |   9 +-
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 138 ++++++++++++++-----
 drivers/net/ethernet/intel/igc/igc_hw.h      |   9 ++
 drivers/net/ethernet/intel/igc/igc_mac.c     |  12 ++
 drivers/net/ethernet/intel/igc/igc_main.c    |   2 +-
 drivers/net/ethernet/intel/igc/igc_phy.c     |  65 ++++++++-
 drivers/net/ethernet/intel/igc/igc_phy.h     |   1 +
 8 files changed, 220 insertions(+), 51 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_base.c b/drivers/net/ethernet/intel/igc/igc_base.c
index 1613b562d17c..ab9120a3127f 100644
--- a/drivers/net/ethernet/intel/igc/igc_base.c
+++ b/drivers/net/ethernet/intel/igc/igc_base.c
@@ -114,11 +114,35 @@ static s32 igc_setup_copper_link_base(struct igc_hw *hw)
 	u32 ctrl;
 
 	ctrl = rd32(IGC_CTRL);
-	ctrl |= IGC_CTRL_SLU;
-	ctrl &= ~(IGC_CTRL_FRCSPD | IGC_CTRL_FRCDPX);
-	wr32(IGC_CTRL, ctrl);
-
-	ret_val = igc_setup_copper_link(hw);
+	ctrl &= ~(IGC_CTRL_FRCSPD | IGC_CTRL_FRCDPX |
+		  IGC_CTRL_SPEED_MASK | IGC_CTRL_FD);
+
+	if (hw->mac.autoneg_enabled) {
+		ctrl |= IGC_CTRL_SLU;
+		wr32(IGC_CTRL, ctrl);
+		ret_val = igc_setup_copper_link(hw);
+	} else {
+		ctrl |= IGC_CTRL_SLU | IGC_CTRL_FRCSPD | IGC_CTRL_FRCDPX;
+
+		switch (hw->mac.forced_speed_duplex) {
+		case IGC_FORCED_10H:
+			ctrl |= IGC_CTRL_SPEED_10;
+			break;
+		case IGC_FORCED_10F:
+			ctrl |= IGC_CTRL_SPEED_10 | IGC_CTRL_FD;
+			break;
+		case IGC_FORCED_100H:
+			ctrl |= IGC_CTRL_SPEED_100;
+			break;
+		case IGC_FORCED_100F:
+			ctrl |= IGC_CTRL_SPEED_100 | IGC_CTRL_FD;
+			break;
+		default:
+			return -IGC_ERR_CONFIG;
+		}
+		wr32(IGC_CTRL, ctrl);
+		ret_val = igc_setup_copper_link(hw);
+	}
 
 	return ret_val;
 }
@@ -443,6 +467,7 @@ static const struct igc_phy_operations igc_phy_ops_base = {
 	.reset			= igc_phy_hw_reset,
 	.read_reg		= igc_read_phy_reg_gpy,
 	.write_reg		= igc_write_phy_reg_gpy,
+	.force_speed_duplex	= igc_force_speed_duplex,
 };
 
 const struct igc_info igc_base_info = {
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index 9482ab11f050..3f504751c2d9 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -129,10 +129,13 @@
 #define IGC_ERR_SWFW_SYNC		13
 
 /* Device Control */
+#define IGC_CTRL_FD		BIT(0)  /* Full Duplex */
 #define IGC_CTRL_RST		0x04000000  /* Global reset */
-
 #define IGC_CTRL_PHY_RST	0x80000000  /* PHY Reset */
 #define IGC_CTRL_SLU		0x00000040  /* Set link up (Force Link) */
+#define IGC_CTRL_SPEED_MASK	GENMASK(10, 8)
+#define IGC_CTRL_SPEED_10	FIELD_PREP(IGC_CTRL_SPEED_MASK, 0)
+#define IGC_CTRL_SPEED_100	FIELD_PREP(IGC_CTRL_SPEED_MASK, 1)
 #define IGC_CTRL_FRCSPD		0x00000800  /* Force Speed */
 #define IGC_CTRL_FRCDPX		0x00001000  /* Force Duplex */
 #define IGC_CTRL_VME		0x40000000  /* IEEE VLAN mode enable */
@@ -673,6 +676,10 @@
 #define IGC_GEN_POLL_TIMEOUT	1920
 
 /* PHY Control Register */
+#define MII_CR_SPEED_MASK	(BIT(6) | BIT(13))
+#define MII_CR_SPEED_10		0x0000	/* SSM=0, SSL=0: 10 Mb/s */
+#define MII_CR_SPEED_100	BIT(13)	/* SSM=0, SSL=1: 100 Mb/s */
+#define MII_CR_DUPLEX_EN	BIT(8)	/* 0 = Half Duplex, 1 = Full Duplex */
 #define MII_CR_RESTART_AUTO_NEG	0x0200  /* Restart auto negotiation */
 #define MII_CR_POWER_DOWN	0x0800  /* Power down */
 #define MII_CR_AUTO_NEG_EN	0x1000  /* Auto Neg Enable */
diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index cfcbf2fdad6e..b103836a895f 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -1914,44 +1914,58 @@ static int igc_ethtool_get_link_ksettings(struct net_device *netdev,
 	ethtool_link_ksettings_add_link_mode(cmd, supported, TP);
 	ethtool_link_ksettings_add_link_mode(cmd, advertising, TP);
 
-	/* advertising link modes */
-	if (hw->phy.autoneg_advertised & ADVERTISE_10_HALF)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 10baseT_Half);
-	if (hw->phy.autoneg_advertised & ADVERTISE_10_FULL)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 10baseT_Full);
-	if (hw->phy.autoneg_advertised & ADVERTISE_100_HALF)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 100baseT_Half);
-	if (hw->phy.autoneg_advertised & ADVERTISE_100_FULL)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 100baseT_Full);
-	if (hw->phy.autoneg_advertised & ADVERTISE_1000_FULL)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 1000baseT_Full);
-	if (hw->phy.autoneg_advertised & ADVERTISE_2500_FULL)
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, 2500baseT_Full);
-
 	/* set autoneg settings */
 	ethtool_link_ksettings_add_link_mode(cmd, supported, Autoneg);
-	ethtool_link_ksettings_add_link_mode(cmd, advertising, Autoneg);
+	if (hw->mac.autoneg_enabled) {
+		ethtool_link_ksettings_add_link_mode(cmd, advertising, Autoneg);
+		cmd->base.autoneg = AUTONEG_ENABLE;
+
+		/* advertising link modes only apply when autoneg is on */
+		if (hw->phy.autoneg_advertised & ADVERTISE_10_HALF)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     10baseT_Half);
+		if (hw->phy.autoneg_advertised & ADVERTISE_10_FULL)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     10baseT_Full);
+		if (hw->phy.autoneg_advertised & ADVERTISE_100_HALF)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     100baseT_Half);
+		if (hw->phy.autoneg_advertised & ADVERTISE_100_FULL)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     100baseT_Full);
+		if (hw->phy.autoneg_advertised & ADVERTISE_1000_FULL)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     1000baseT_Full);
+		if (hw->phy.autoneg_advertised & ADVERTISE_2500_FULL)
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     2500baseT_Full);
+
+		/* Set pause flow control advertising */
+		switch (hw->fc.requested_mode) {
+		case igc_fc_full:
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     Pause);
+			break;
+		case igc_fc_rx_pause:
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     Pause);
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     Asym_Pause);
+			break;
+		case igc_fc_tx_pause:
+			ethtool_link_ksettings_add_link_mode(cmd, advertising,
+							     Asym_Pause);
+			break;
+		default:
+			break;
+		}
+	} else {
+		cmd->base.autoneg = AUTONEG_DISABLE;
+	}
 
-	/* Set pause flow control settings */
+	/* Pause is always supported */
 	ethtool_link_ksettings_add_link_mode(cmd, supported, Pause);
 
-	switch (hw->fc.requested_mode) {
-	case igc_fc_full:
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, Pause);
-		break;
-	case igc_fc_rx_pause:
-		ethtool_link_ksettings_add_link_mode(cmd, advertising, Pause);
-		ethtool_link_ksettings_add_link_mode(cmd, advertising,
-						     Asym_Pause);
-		break;
-	case igc_fc_tx_pause:
-		ethtool_link_ksettings_add_link_mode(cmd, advertising,
-						     Asym_Pause);
-		break;
-	default:
-		break;
-	}
-
 	status = pm_runtime_suspended(&adapter->pdev->dev) ?
 		 0 : rd32(IGC_STATUS);
 
@@ -1983,7 +1997,6 @@ static int igc_ethtool_get_link_ksettings(struct net_device *netdev,
 		cmd->base.duplex = DUPLEX_UNKNOWN;
 	}
 	cmd->base.speed = speed;
-	cmd->base.autoneg = AUTONEG_ENABLE;
 
 	/* MDI-X => 2; MDI =>1; Invalid =>0 */
 	if (hw->phy.media_type == igc_media_type_copper)
@@ -2000,6 +2013,37 @@ static int igc_ethtool_get_link_ksettings(struct net_device *netdev,
 	return 0;
 }
 
+/**
+ * igc_handle_autoneg_disabled - Configure forced speed/duplex settings
+ * @adapter: private driver structure
+ * @speed: requested speed (must be SPEED_10 or SPEED_100)
+ * @duplex: requested duplex
+ *
+ * Records forced speed/duplex when autoneg is disabled.
+ * Caller must validate speed before calling this function.
+ */
+static void igc_handle_autoneg_disabled(struct igc_adapter *adapter, u32 speed,
+					u8 duplex)
+{
+	struct igc_mac_info *mac = &adapter->hw.mac;
+
+	switch (speed) {
+	case SPEED_10:
+		mac->forced_speed_duplex = (duplex == DUPLEX_FULL) ?
+			IGC_FORCED_10F : IGC_FORCED_10H;
+		break;
+	case SPEED_100:
+		mac->forced_speed_duplex = (duplex == DUPLEX_FULL) ?
+			IGC_FORCED_100F : IGC_FORCED_100H;
+		break;
+	default:
+		WARN_ONCE(1, "Unsupported speed %u\n", speed);
+		return;
+	}
+
+	mac->autoneg_enabled = false;
+}
+
 /**
  * igc_handle_autoneg_enabled - Configure autonegotiation advertisement
  * @adapter: private driver structure
@@ -2038,6 +2082,7 @@ static void igc_handle_autoneg_enabled(struct igc_adapter *adapter,
 						  10baseT_Half))
 		advertised |= ADVERTISE_10_HALF;
 
+	hw->mac.autoneg_enabled = true;
 	hw->phy.autoneg_advertised = advertised;
 	if (adapter->fc_autoneg)
 		hw->fc.requested_mode = igc_fc_default;
@@ -2059,6 +2104,12 @@ igc_ethtool_set_link_ksettings(struct net_device *netdev,
 		return -EINVAL;
 	}
 
+	if (cmd->base.autoneg != AUTONEG_ENABLE &&
+	    cmd->base.autoneg != AUTONEG_DISABLE) {
+		netdev_info(dev, "Unsupported autoneg setting\n");
+		return -EINVAL;
+	}
+
 	/* MDI setting is only allowed when autoneg enabled because
 	 * some hardware doesn't allow MDI setting when speed or
 	 * duplex is forced.
@@ -2071,14 +2122,25 @@ igc_ethtool_set_link_ksettings(struct net_device *netdev,
 		}
 	}
 
+	if (cmd->base.autoneg == AUTONEG_DISABLE) {
+		if (cmd->base.speed != SPEED_10 && cmd->base.speed != SPEED_100) {
+			netdev_info(dev, "Unsupported speed for forced link\n");
+			return -EINVAL;
+		}
+		if (cmd->base.duplex != DUPLEX_HALF && cmd->base.duplex != DUPLEX_FULL) {
+			netdev_info(dev, "Duplex must be half or full for forced link\n");
+			return -EINVAL;
+		}
+	}
+
 	while (test_and_set_bit(__IGC_RESETTING, &adapter->state))
 		usleep_range(1000, 2000);
 
-	if (cmd->base.autoneg == AUTONEG_ENABLE) {
+	if (cmd->base.autoneg == AUTONEG_ENABLE)
 		igc_handle_autoneg_enabled(adapter, cmd);
-	} else {
-		netdev_info(dev, "Force mode currently not supported\n");
-	}
+	else
+		igc_handle_autoneg_disabled(adapter, cmd->base.speed,
+					    cmd->base.duplex);
 
 	/* MDI-X => 2; MDI => 1; Auto => 3 */
 	if (cmd->base.eth_tp_mdix_ctrl) {
diff --git a/drivers/net/ethernet/intel/igc/igc_hw.h b/drivers/net/ethernet/intel/igc/igc_hw.h
index 86ab8f566f44..62aaee55668a 100644
--- a/drivers/net/ethernet/intel/igc/igc_hw.h
+++ b/drivers/net/ethernet/intel/igc/igc_hw.h
@@ -73,6 +73,13 @@ struct igc_info {
 
 extern const struct igc_info igc_base_info;
 
+enum igc_forced_speed_duplex {
+	IGC_FORCED_10H,
+	IGC_FORCED_10F,
+	IGC_FORCED_100H,
+	IGC_FORCED_100F,
+};
+
 struct igc_mac_info {
 	struct igc_mac_operations ops;
 
@@ -93,6 +100,8 @@ struct igc_mac_info {
 	bool arc_subsystem_valid;
 
 	bool get_link_status;
+	bool autoneg_enabled;
+	enum igc_forced_speed_duplex forced_speed_duplex;
 };
 
 struct igc_nvm_operations {
diff --git a/drivers/net/ethernet/intel/igc/igc_mac.c b/drivers/net/ethernet/intel/igc/igc_mac.c
index 0a3d3f357505..d6f3f6618469 100644
--- a/drivers/net/ethernet/intel/igc/igc_mac.c
+++ b/drivers/net/ethernet/intel/igc/igc_mac.c
@@ -446,6 +446,17 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	u16 speed, duplex;
 	s32 ret_val = 0;
 
+	/* Without autoneg, flow control capability is not exchanged with the
+	 * link partner. IEEE 802.3 prohibits flow control in half-duplex mode.
+	 */
+	if (!hw->mac.autoneg_enabled) {
+		if (hw->mac.forced_speed_duplex == IGC_FORCED_10H ||
+		    hw->mac.forced_speed_duplex == IGC_FORCED_100H)
+			hw->fc.current_mode = igc_fc_none;
+
+		goto force_fc;
+	}
+
 	/* In auto-neg, we need to check and see if Auto-Neg has completed,
 	 * and if so, how the PHY and link partner has flow control
 	 * configured.
@@ -607,6 +618,7 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
 	/* Now we call a subroutine to actually force the MAC
 	 * controller to use the correct flow control settings.
 	 */
+force_fc:
 	ret_val = igc_force_mac_fc(hw);
 	if (ret_val) {
 		hw_dbg("Error forcing flow control settings\n");
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 72bc5128d8b8..437e1d1ef1e4 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7298,7 +7298,7 @@ static int igc_probe(struct pci_dev *pdev,
 	/* Initialize link properties that are user-changeable */
 	adapter->fc_autoneg = true;
 	hw->phy.autoneg_advertised = 0xaf;
-
+	hw->mac.autoneg_enabled = true;
 	hw->fc.requested_mode = igc_fc_default;
 	hw->fc.current_mode = igc_fc_default;
 
diff --git a/drivers/net/ethernet/intel/igc/igc_phy.c b/drivers/net/ethernet/intel/igc/igc_phy.c
index 6c4d204aecfa..4cf737fb3b21 100644
--- a/drivers/net/ethernet/intel/igc/igc_phy.c
+++ b/drivers/net/ethernet/intel/igc/igc_phy.c
@@ -494,12 +494,20 @@ s32 igc_setup_copper_link(struct igc_hw *hw)
 	s32 ret_val = 0;
 	bool link;
 
-	/* Setup autoneg and flow control advertisement and perform
-	 * autonegotiation.
-	 */
-	ret_val = igc_copper_link_autoneg(hw);
-	if (ret_val)
-		goto out;
+	if (hw->mac.autoneg_enabled) {
+		/* Setup autoneg and flow control advertisement and perform
+		 * autonegotiation.
+		 */
+		ret_val = igc_copper_link_autoneg(hw);
+		if (ret_val)
+			goto out;
+	} else {
+		ret_val = hw->phy.ops.force_speed_duplex(hw);
+		if (ret_val) {
+			hw_dbg("Error Forcing Speed/Duplex\n");
+			goto out;
+		}
+	}
 
 	/* Check link status. Wait up to 100 microseconds for link to become
 	 * valid.
@@ -778,3 +786,48 @@ u16 igc_read_phy_fw_version(struct igc_hw *hw)
 
 	return gphy_version;
 }
+
+/**
+ * igc_force_speed_duplex - Force PHY speed and duplex settings
+ * @hw: pointer to the HW structure
+ *
+ * Programs the GPY PHY control register to disable autonegotiation
+ * and force the speed/duplex indicated by hw->mac.forced_speed_duplex.
+ */
+s32 igc_force_speed_duplex(struct igc_hw *hw)
+{
+	struct igc_phy_info *phy = &hw->phy;
+	u16 phy_ctrl;
+	s32 ret_val;
+
+	ret_val = phy->ops.read_reg(hw, PHY_CONTROL, &phy_ctrl);
+	if (ret_val)
+		return ret_val;
+
+	phy_ctrl &= ~(MII_CR_SPEED_MASK | MII_CR_DUPLEX_EN |
+		      MII_CR_AUTO_NEG_EN | MII_CR_RESTART_AUTO_NEG);
+
+	switch (hw->mac.forced_speed_duplex) {
+	case IGC_FORCED_10H:
+		phy_ctrl |= MII_CR_SPEED_10;
+		break;
+	case IGC_FORCED_10F:
+		phy_ctrl |= MII_CR_SPEED_10 | MII_CR_DUPLEX_EN;
+		break;
+	case IGC_FORCED_100H:
+		phy_ctrl |= MII_CR_SPEED_100;
+		break;
+	case IGC_FORCED_100F:
+		phy_ctrl |= MII_CR_SPEED_100 | MII_CR_DUPLEX_EN;
+		break;
+	default:
+		return -IGC_ERR_CONFIG;
+	}
+
+	ret_val = phy->ops.write_reg(hw, PHY_CONTROL, phy_ctrl);
+	if (ret_val)
+		return ret_val;
+
+	hw->mac.get_link_status = true;
+	return 0;
+}
diff --git a/drivers/net/ethernet/intel/igc/igc_phy.h b/drivers/net/ethernet/intel/igc/igc_phy.h
index 832a7e359f18..d37a89174826 100644
--- a/drivers/net/ethernet/intel/igc/igc_phy.h
+++ b/drivers/net/ethernet/intel/igc/igc_phy.h
@@ -18,5 +18,6 @@ void igc_power_down_phy_copper(struct igc_hw *hw);
 s32 igc_write_phy_reg_gpy(struct igc_hw *hw, u32 offset, u16 data);
 s32 igc_read_phy_reg_gpy(struct igc_hw *hw, u32 offset, u16 *data);
 u16 igc_read_phy_fw_version(struct igc_hw *hw);
+s32 igc_force_speed_duplex(struct igc_hw *hw);
 
 #endif
-- 
2.43.0

Re: [PATCH iwl-next v5 0/4] igc: add support for forcing link speed without autonegotiation

[Simon Horman]

On Fri, May 08, 2026 at 05:47:02AM +0800, KhaiWenTan wrote:
> From: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
> 
> This series adds support for forcing 10/100 Mb/s link speed via ethtool
> when autonegotiation is disabled on the igc driver.
> 
> Changes in v5:
> - add removal justification to include copper context in commit
>   description for igc: remove unused autoneg_failed field (Paul)
> - check that cmd->base.duplex is either DUPLEX_HALF or DUPLEX_FULL
>   in igc_ethtool_set_link_ksettings() (Simon)
> - dynamically override hw->fc.current_mode to igc_fc_none during
>   link configuration instead of mutating requested_mode (Simon)
> 
> Changes in v4:
> - Validate that autoneg is AUTONEG_ENABLE or AUTONEG_DISABLE early
>   in igc_ethtool_set_link_ksettings() to avoid passing unexpected
>   values to igc_handle_autoneg_disabled(). (Simon Horman)
> 
> Changes in v3:
> - Modify condition from "if (duplex == DUPLEX_HALF)" to
>   "if (duplex != DUPLEX_FULL)". (Simon Horman)
> 
> Changes in v2:
> - When forcing half-duplex, set hw->fc.requested_mode = igc_fc_none,
>   since half-duplex cannot support flow control per IEEE 802.3.
>   (Simon Horman)
> - Split the original single patch into three patches for clarity:
>   patches 1 and 2 are preparatory cleanups; patch 3 carries the
>   functional change.

Thanks for your persistence.

For the series:

Reviewed-by: Simon Horman <horms@kernel.org>