From 8fdfa207afdd9274efa8143861622867ea8fec22 Mon Sep 17 00:00:00 2001 From: Kurt Kanzenbach Date: Thu, 20 Nov 2025 09:18:29 +0100 Subject: [PATCH] igc: Restore default Qbv schedule when changing channels [ Upstream commit 41a9a6826f20a524242a6c984845c4855f629841 ] The Multi-queue Priority (MQPRIO) and Earliest TxTime First (ETF) offloads utilize the Time Sensitive Networking (TSN) Tx mode. This mode is always coupled to IEEE 802.1Qbv time aware shaper (Qbv). Therefore, the driver sets a default Qbv schedule of all gates opened and a cycle time of 1s. This schedule is set during probe. However, the following sequence of events lead to Tx issues: - Boot a dual core system igc_probe(): igc_tsn_clear_schedule(): -> Default Schedule is set Note: At this point the driver has allocated two Tx/Rx queues, because there are only two CPUs. - ethtool -L enp3s0 combined 4 igc_ethtool_set_channels(): igc_reinit_queues() -> Default schedule is gone, per Tx ring start and end time are zero - tc qdisc replace dev enp3s0 handle 100 parent root mqprio \ num_tc 4 map 3 3 2 2 0 1 1 1 3 3 3 3 3 3 3 3 \ queues 1@0 1@1 1@2 1@3 hw 1 igc_tsn_offload_apply(): igc_tsn_enable_offload(): -> Writes zeros to IGC_STQT(i) and IGC_ENDQT(i), causing Tx to stall/fail Therefore, restore the default Qbv schedule after changing the number of channels. Furthermore, add a restriction to not allow queue reconfiguration when TSN/Qbv is enabled, because it may lead to inconsistent states. Fixes: c814a2d2d48f ("igc: Use default cycle 'start' and 'end' values for queues") Signed-off-by: Kurt Kanzenbach Reviewed-by: Aleksandr Loktionov Tested-by: Avigail Dahan Acked-by: Vinicius Costa Gomes Signed-off-by: Tony Nguyen Signed-off-by: Sasha Levin --- drivers/net/ethernet/intel/igc/igc_ethtool.c | 4 ++-- drivers/net/ethernet/intel/igc/igc_main.c | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c index 5b0c6f433767..f4179b814eaf 100644 --- a/drivers/net/ethernet/intel/igc/igc_ethtool.c +++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c @@ -1540,8 +1540,8 @@ static int igc_ethtool_set_channels(struct net_device *netdev, if (ch->other_count != NON_Q_VECTORS) return -EINVAL; - /* Do not allow channel reconfiguration when mqprio is enabled */ - if (adapter->strict_priority_enable) + /* Do not allow channel reconfiguration when any TSN qdisc is enabled */ + if (adapter->flags & IGC_FLAG_TSN_ANY_ENABLED) return -EINVAL; /* Verify the number of channels doesn't exceed hw limits */ diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 9ba41a427e14..18dad521aefc 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -7582,6 +7582,11 @@ int igc_reinit_queues(struct igc_adapter *adapter) if (netif_running(netdev)) err = igc_open(netdev); + if (!err) { + /* Restore default IEEE 802.1Qbv schedule after queue reinit */ + igc_tsn_clear_schedule(adapter); + } + return err; }