[PATCH net-next 1/2] net: lan743x: set interrupt moderation timer based on link speed
From: Dhanushkalyan G
Date: Mon Aug 03 2026 - 09:11:21 EST
From: Thangaraj Samynathan <Thangaraj.S@xxxxxxxxxxxxx>
The driver programs a single fixed interrupt moderation timer into every
INT_MOD_CFG register at interrupt open, regardless of the negotiated link
speed. A fixed value is a poor trade-off across the supported speed
range: it is too coarse at low speeds and not aggressive enough at 2.5G.
Set the moderation timer as a function of the negotiated link speed in
the MAC link-up path: 64 us at 2.5G, 150 us at 1G, and 330 us at
100M/10M. The interrupt-vector-to-timer mapping (INT_MOD_MAP) is static,
so it stays programmed once at interrupt open; only the timer value
(INT_MOD_CFG) is updated, from the new lan743x_config_int_mod() helper,
when the link comes up.
Signed-off-by: Thangaraj Samynathan <Thangaraj.S@xxxxxxxxxxxxx>
Signed-off-by: Dhanushkalyan G <Dhanushkalyan.G@xxxxxxxxxxxxx>
---
drivers/net/ethernet/microchip/lan743x_main.c | 51 ++++++++++++++-----
drivers/net/ethernet/microchip/lan743x_main.h | 5 +-
2 files changed, 42 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index f3332417162e..20d6a48ca0bb 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -627,18 +627,12 @@ static int lan743x_intr_open(struct lan743x_adapter *adapter)
lan743x_csr_write(adapter, INT_VEC_EN_SET,
INT_VEC_EN_(0));
+ /* The interrupt-vector-to-moderation-timer mapping is static, so
+ * program it once here. The timer values themselves are set later
+ * (per link speed) via lan743x_config_int_mod().
+ */
if (!(adapter->csr.flags & LAN743X_CSR_FLAG_IS_A0)) {
- lan743x_csr_write(adapter, INT_MOD_CFG0, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG1, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG2, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG3, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG4, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG5, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG6, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG7, LAN743X_INT_MOD);
if (adapter->is_pci11x1x) {
- lan743x_csr_write(adapter, INT_MOD_CFG8, LAN743X_INT_MOD);
- lan743x_csr_write(adapter, INT_MOD_CFG9, LAN743X_INT_MOD);
lan743x_csr_write(adapter, INT_MOD_MAP0, 0x00007654);
lan743x_csr_write(adapter, INT_MOD_MAP1, 0x00003210);
} else {
@@ -3036,6 +3030,28 @@ static void lan743x_phylink_mac_link_down(struct phylink_config *config,
netif_tx_stop_all_queues(netdev);
}
+/* Program the interrupt moderation timer value into the per-vector
+ * INT_MOD_CFG registers. Only the timer value is written here; the vector
+ * mapping (INT_MOD_MAP) is static and is set once at interrupt open.
+ */
+static void lan743x_config_int_mod(struct lan743x_adapter *adapter, u32 int_mod)
+{
+ if (!(adapter->csr.flags & LAN743X_CSR_FLAG_IS_A0)) {
+ lan743x_csr_write(adapter, INT_MOD_CFG0, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG1, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG2, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG3, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG4, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG5, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG6, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG7, int_mod);
+ if (adapter->is_pci11x1x) {
+ lan743x_csr_write(adapter, INT_MOD_CFG8, int_mod);
+ lan743x_csr_write(adapter, INT_MOD_CFG9, int_mod);
+ }
+ }
+}
+
static void lan743x_phylink_mac_link_up(struct phylink_config *config,
struct phy_device *phydev,
unsigned int link_an_mode,
@@ -3045,6 +3061,7 @@ static void lan743x_phylink_mac_link_up(struct phylink_config *config,
{
struct net_device *netdev = to_net_dev(config->dev);
struct lan743x_adapter *adapter = netdev_priv(netdev);
+ u32 int_mod;
int mac_cr;
u8 cap;
@@ -3053,12 +3070,18 @@ static void lan743x_phylink_mac_link_up(struct phylink_config *config,
* Resulting value corresponds to SPEED_10
*/
mac_cr &= ~(MAC_CR_CFG_H_ | MAC_CR_CFG_L_);
- if (speed == SPEED_2500)
+ if (speed == SPEED_2500) {
mac_cr |= MAC_CR_CFG_H_ | MAC_CR_CFG_L_;
- else if (speed == SPEED_1000)
+ int_mod = LAN743X_INT_MOD_2_5G;
+ } else if (speed == SPEED_1000) {
mac_cr |= MAC_CR_CFG_H_;
- else if (speed == SPEED_100)
+ int_mod = LAN743X_INT_MOD_1G;
+ } else if (speed == SPEED_100) {
mac_cr |= MAC_CR_CFG_L_;
+ int_mod = LAN743X_INT_MOD_100M;
+ } else {
+ int_mod = LAN743X_INT_MOD_10M;
+ }
if (duplex == DUPLEX_FULL)
mac_cr |= MAC_CR_DPX_;
@@ -3067,6 +3090,8 @@ static void lan743x_phylink_mac_link_up(struct phylink_config *config,
lan743x_csr_write(adapter, MAC_CR, mac_cr);
+ lan743x_config_int_mod(adapter, int_mod);
+
lan743x_ptp_update_latency(adapter, speed);
/* Flow Control operation */
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index 160d94a7cee6..c4a3de7fe107 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -861,7 +861,10 @@ struct lan743x_adapter;
#define LAN743X_USED_RX_CHANNELS (4)
#define LAN743X_USED_TX_CHANNELS (1)
#define PCI11X1X_USED_TX_CHANNELS (4)
-#define LAN743X_INT_MOD (400)
+#define LAN743X_INT_MOD_2_5G (64)
+#define LAN743X_INT_MOD_1G (150)
+#define LAN743X_INT_MOD_100M (330)
+#define LAN743X_INT_MOD_10M (330)
#if (LAN743X_USED_RX_CHANNELS > LAN743X_MAX_RX_CHANNELS)
#error Invalid LAN743X_USED_RX_CHANNELS
--
2.34.1