Hi, Kurt Kanzenbach <[email protected]> writes:
> The MQPRIO (and ETF) offload utilizes the TSN Tx mode. This mode is always > coupled to 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 > 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 CPU(s). > > - 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) -> Boom > > Therefore, restore the default Qbv schedule after changing the amount of > channels. > Couple of questions: - Would it make sense to mark this patch as a fix? - What would happen if the user added a Qbv schedule (not the default one) and then changed the number of queues? My concern is that 'tc qdisc' would show the custom user schedule and the hardware would be "running" the default schedule, this inconsistency is not ideal. In any case, it would be a separate patch. > Signed-off-by: Kurt Kanzenbach <[email protected]> > --- > drivers/net/ethernet/intel/igc/igc_main.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/net/ethernet/intel/igc/igc_main.c > b/drivers/net/ethernet/intel/igc/igc_main.c > index > 728d7ca5338bf27c3ce50a2a497b238c38cfa338..e4200fcb2682ccd5b57abb0d2b8e4eb30df117df > 100644 > --- a/drivers/net/ethernet/intel/igc/igc_main.c > +++ b/drivers/net/ethernet/intel/igc/igc_main.c > @@ -7761,6 +7761,8 @@ int igc_reinit_queues(struct igc_adapter *adapter) > if (netif_running(netdev)) > err = igc_open(netdev); > > + igc_tsn_clear_schedule(adapter); > + > return err; > } > > > --- > base-commit: 6fc33710cd6c55397e606eeb544bdf56ee87aae5 > change-id: 20251107-igc_mqprio_channels-2329166e898b > > Best regards, > -- > Kurt Kanzenbach <[email protected]> > Cheers, -- Vinicius
