Commit 41a9a682 authored by Kurt Kanzenbach's avatar Kurt Kanzenbach Committed by Tony Nguyen
Browse files

igc: Restore default Qbv schedule when changing channels 



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: c814a2d2 ("igc: Use default cycle 'start' and 'end' values for queues")
Signed-off-by: default avatarKurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: default avatarAleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: default avatarAvigail Dahan <avigailx.dahan@intel.com>
Acked-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
parent 01139a2c

drivers/net/ethernet/intel/igc/igc_ethtool.c

+2 −2
Original line number Diff line number Diff line
@@ -1565,8 +1565,8 @@ 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 */

drivers/net/ethernet/intel/igc/igc_main.c

+5 −0
Original line number Diff line number Diff line
@@ -7759,6 +7759,11 @@ 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;

}