[PATCH v2] dts: testpmd link check on port start

[Patrick Robb <probb@iol.unh.edu>]

When running our existing DTS testsuites on a new
NIC we observed packets would not transmit from
the traffic generator to the system under test
even after DPDK testpmd and the NIC under test
had indicated readiness. After investigation, we
determined that the existing readiness check in DTS
for testpmd start (checking that port is started)
is insufficient, because on some systems the link
will remain down for some measurable time, creating
a race condition between the testpmd port's link
coming up and the DTS execution reaching the packet
transmission step. This change will ensure that
testpmd start will block until the port is reporting
that its link is up. In addition, the interval in
between checking the link state has been reduced in
order to speed up the execution.

Signed-off-by: Patrick Robb <probb@iol.unh.edu>
Tested-by: Patrick Robb <probb@iol.unh.edu>
---
 dts/api/testpmd/__init__.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/dts/api/testpmd/__init__.py b/dts/api/testpmd/__init__.py
index aadb7f4e70..49a847494a 100644
--- a/dts/api/testpmd/__init__.py
+++ b/dts/api/testpmd/__init__.py
@@ -93,6 +93,9 @@ def _requires_started_ports(func: TestPmdMethod) -> TestPmdMethod:
 
     Args:
         func: The :class:`TestPmd` method to decorate.
+
+    Raises:
+        InteractiveCommandExecutionError: If the ports has been started but a port link will not come up.
     """
 
     @functools.wraps(func)
@@ -100,6 +103,10 @@ def _wrapper(self: "TestPmd", *args: P.args, **kwargs: P.kwargs) -> Any:
         if not self.ports_started:
             self._logger.debug("Ports need to be started to continue.")
             self.start_all_ports()
+        if get_ctx().topology.type is not LinkTopology.NO_LINK:
+            for port in self.ports:
+                if not self.wait_link_status_up(port.id):
+                    raise InteractiveCommandExecutionError(f"Port {port.id} link failed to come up.")
 
         return func(self, *args, **kwargs)
 
@@ -265,7 +272,7 @@ def wait_link_status_up(self, port_id: int, timeout=SETTINGS.timeout) -> bool:
             port_info = self.send_command(f"show port info {port_id}")
             if "Link status: up" in port_info:
                 break
-            time.sleep(0.5)
+            time.sleep(0.25)
         else:
             self._logger.error(f"The link for port {port_id} did not come up in the given timeout.")
         return "Link status: up" in port_info
-- 
2.49.0