[PATCH iwl-next v2 3/3] igc: add support for forcing link speed without autonegotiation

KhaiWenTan
2026-04-16T02:18:42Z

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: KhaiWenTan <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 | 131 +++++++++++++------
drivers/net/ethernet/intel/igc/igc_hw.h | 9 ++
drivers/net/ethernet/intel/igc/igc_mac.c | 10 ++
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, 211 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..5bd37d1be168 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 +2013,41 @@ 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;
+
+ /* Half-duplex cannot support flow control per IEEE 802.3 */
+ if (duplex == DUPLEX_HALF)
+ adapter->hw.fc.requested_mode = igc_fc_none;
+}
+
/**
* igc_handle_autoneg_enabled - Configure autonegotiation advertisement
* @adapter: private driver structure
@@ -2038,6 +2086,7 @@ 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;
@@ -2071,14 +2120,20 @@ igc_ethtool_set_link_ksettings(struct net_device *netdev,
}
}

+ if (cmd->base.autoneg == AUTONEG_DISABLE &&
+ cmd->base.speed != SPEED_10 && cmd->base.speed != SPEED_100) {
+ netdev_info(dev, "Unsupported speed 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 142beb9ae557..8bbb6d5581c7 100644
--- a/drivers/net/ethernet/intel/igc/igc_mac.c
+++ b/drivers/net/ethernet/intel/igc/igc_mac.c
@@ -446,6 +446,16 @@ s32 igc_config_fc_after_link_up(struct igc_hw *hw)
u16 speed, duplex;
s32 ret_val = 0;

+ /* When autoneg is disabled, force the MAC flow control settings
+ * to match the "fc" parameter.
+ */
+ if (!hw->mac.autoneg_enabled) {
+ 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.
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