The querier-interval test adds h1 (currently a slave of the VRF created
by simple_if_init) to a temporary bridge br1 acting as an outside IGMP
querier. The kernel VRF driver (drivers/net/vrf.c) calls cycle_netdev()
on every slave add and remove, toggling the interface admin-down then up.
Phylink takes the PHY down during the admin-down half of that cycle.
Since h1 and swp1 are cable-connected, swp1 also loses its link may need
several seconds to re-negotiate.

Use setup_wait_dev $h1 0 which waits for h1 to return to UP state, so the
test can rely on the link being back up at this point.

Fixes: 4d8610ee8bd77 ("selftests: net: bridge: add vlan mcast_querier_interval tests")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 tools/testing/selftests/net/forwarding/bridge_vlan_mcast.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/net/forwarding/bridge_vlan_mcast.sh b/tools/testing/selftests/net/forwarding/bridge_vlan_mcast.sh
index 72dfbeaf56b92..e8031f68200ad 100755
--- a/tools/testing/selftests/net/forwarding/bridge_vlan_mcast.sh
+++ b/tools/testing/selftests/net/forwarding/bridge_vlan_mcast.sh
@@ -414,6 +414,7 @@ vlmc_querier_intvl_test()
 	bridge vlan add vid 10 dev br1 self pvid untagged
 	ip link set dev $h1 master br1
 	ip link set dev br1 up
+	setup_wait_dev $h1 0
 	bridge vlan add vid 10 dev $h1 master
 	bridge vlan global set vid 10 dev br1 mcast_snooping 1 mcast_querier 1
 	sleep 2
-- 
2.53.0