[PATCH net] net: ti: icssg-prueth: Fix switch mode for offload and non-offload cases

[Meghana Malladi <m-malladi@ti.com>]

Non-offloaded switch mode is failing to forward packets. Following fixes
ensure smooth operation of switch mode in both offload and non-offload cases:

- Fix NULL dereference in icssg_enable_fw_offload() when second emac
  slot is uninitialized during first port open
- Set port_vlan on both emacs when bridge is formed; previously only
  the second port was set, causing TX stalls in switch offload mode
- Track UC/MC flooding state and restore it after firmware restart in
  non-offload bridge mode; restart cleared IFF_PROMISC-driven flooding,
  breaking unicast forwarding across bridge ports
- Defer emac_adjust_link() to after prueth_emac_start() so R30 FORWARD
  commands don't time out with PRU not running, leaving stale R30 values
  that caused prueth_emac_restart() to fail in non-offload bridge mode

Fixes: 161087db66d6b ("net: ti: icssg-prueth: Add Support for Multicast filtering with VLAN in HSR mode")
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
---
 drivers/net/ethernet/ti/icssg/icssg_prueth.c | 47 +++++++++++++++-----
 drivers/net/ethernet/ti/icssg/icssg_prueth.h |  4 ++
 2 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.c b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
index 591be5c8056b..9afda5da3ca3 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.c
@@ -213,6 +213,8 @@ static void icssg_enable_fw_offload(struct prueth *prueth)
 
 	for (mac = PRUETH_MAC0; mac < PRUETH_NUM_MACS; mac++) {
 		emac = prueth->emac[mac];
+		if (!emac)
+			continue;
 		if (prueth->is_hsr_offload_mode) {
 			if (emac->ndev->features & NETIF_F_HW_HSR_TAG_RM)
 				icssg_set_port_state(emac, ICSSG_EMAC_HSR_RX_OFFLOAD_ENABLE);
@@ -241,6 +243,16 @@ static void icssg_enable_fw_offload(struct prueth *prueth)
 					icssg_set_port_state(emac, ICSSG_EMAC_PORT_VLAN_AWARE_ENABLE);
 			}
 		}
+
+		/* Re-apply flooding state cleared by firmware restart.
+		 * Not needed in switch mode; FDB handles forwarding there.
+		 */
+		if (!prueth->is_switch_mode && netif_running(emac->ndev)) {
+			if (emac->uc_flooding_enabled)
+				icssg_set_port_state(emac, ICSSG_EMAC_PORT_UC_FLOODING_ENABLE);
+			if (emac->mc_flooding_enabled)
+				icssg_set_port_state(emac, ICSSG_EMAC_PORT_MC_FLOODING_ENABLE);
+		}
 	}
 }
 
@@ -278,13 +290,22 @@ static int prueth_emac_common_start(struct prueth *prueth)
 		ret = icssg_config(prueth, emac, slice);
 		if (ret)
 			goto disable_class;
+	}
+
+	ret = prueth_emac_start(prueth);
+	if (ret)
+		goto disable_class;
+
+	/* Reset link state and reconfigure after firmware is running.
+	 * Must be done after prueth_emac_start() so that R30 commands
+	 * (e.g. ICSSG_EMAC_PORT_FORWARD from emac_adjust_link) reach
+	 * the PRU firmware instead of timing out with stale R30 values.
+	 */
+	for (slice = 0; slice < PRUETH_NUM_MACS; slice++) {
+		emac = prueth->emac[slice];
+		if (!emac)
+			continue;
 
-		/* Reset link state to force reconfiguration in
-		 * emac_adjust_link(). Without this, if the link was already up
-		 * before restart, emac_adjust_link() won't detect any state
-		 * change and will skip critical configuration like writing
-		 * speed to firmware.
-		 */
 		emac->link = 0;
 
 		mutex_lock(&emac->ndev->phydev->lock);
@@ -292,10 +313,6 @@ static int prueth_emac_common_start(struct prueth *prueth)
 		mutex_unlock(&emac->ndev->phydev->lock);
 	}
 
-	ret = prueth_emac_start(prueth);
-	if (ret)
-		goto disable_class;
-
 	emac = prueth->emac[ICSS_SLICE0] ? prueth->emac[ICSS_SLICE0] :
 	       prueth->emac[ICSS_SLICE1];
 	ret = icss_iep_init(emac->iep, &prueth_iep_clockops,
@@ -1288,14 +1305,21 @@ static void emac_ndo_set_rx_mode_work(struct work_struct *work)
 	if (promisc) {
 		icssg_set_port_state(emac, ICSSG_EMAC_PORT_UC_FLOODING_ENABLE);
 		icssg_set_port_state(emac, ICSSG_EMAC_PORT_MC_FLOODING_ENABLE);
+		emac->uc_flooding_enabled = true;
+		emac->mc_flooding_enabled = true;
 		return;
 	}
 
 	if (allmulti) {
 		icssg_set_port_state(emac, ICSSG_EMAC_PORT_MC_FLOODING_ENABLE);
+		emac->mc_flooding_enabled = true;
+		emac->uc_flooding_enabled = false;
 		return;
 	}
 
+	emac->uc_flooding_enabled = false;
+	emac->mc_flooding_enabled = false;
+
 	if (emac->prueth->is_hsr_offload_mode) {
 		/* Track basic add/delete via callbacks */
 		__dev_mc_sync(ndev, icssg_prueth_hsr_add_mcast,
@@ -1919,7 +1943,8 @@ static int prueth_netdevice_port_link(struct net_device *ndev,
 		    prueth->br_members & BIT(PRUETH_PORT_MII1)) {
 			prueth->is_switch_mode = true;
 			prueth->default_vlan = PRUETH_DFLT_VLAN_SW;
-			emac->port_vlan = prueth->default_vlan;
+			prueth->emac[PRUETH_MAC0]->port_vlan = prueth->default_vlan;
+			prueth->emac[PRUETH_MAC1]->port_vlan = prueth->default_vlan;
 			icssg_change_mode(prueth);
 		}
 	}
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
index df93d15c5b78..832e654a102c 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
@@ -242,6 +242,10 @@ struct prueth_emac {
 	bool offload_fwd_mark;
 	int port_vlan;
 
+	/* UC/MC flooding state - preserved across firmware restarts */
+	unsigned int uc_flooding_enabled : 1;
+	unsigned int mc_flooding_enabled : 1;
+
 	struct delayed_work stats_work;
 	u64 stats[ICSSG_NUM_MIIG_STATS];
 	u64 pa_stats[ICSSG_NUM_PA_STATS];

base-commit: 99b43ede9e355ba35244cc9470bf1819774ce39d
-- 
2.43.0