[RFC PATCH] dts: restore unbinded ports to initial state

[Koushik Bhargav Nimoji]

Once DTS completes execution, it re-binds ports to the drivers
they were initially bound to. However, when a port was not bound
to any drivers, it would raise an error when the bind command was
run. This patch resolves this issue, and properly unbinds a driver
if it was unbound before DTS execution began.

Signed-off-by: Koushik Bhargav Nimoji <knimoji at iol.unh.edu>
---
 dts/framework/testbed_model/linux_session.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/dts/framework/testbed_model/linux_session.py b/dts/framework/testbed_model/linux_session.py
index c118f803b6..1297c301b5 100644
--- a/dts/framework/testbed_model/linux_session.py
+++ b/dts/framework/testbed_model/linux_session.py
@@ -272,13 +272,19 @@ def bind_ports_to_driver(self, ports: list[Port], driver_name: str) -> None:
         """
         ports_pci_addrs = " ".join(port.pci for port in ports)
 
-        self.send_command(
-            f"{self.devbind_script_path} -b {driver_name} --force {ports_pci_addrs}",
-            privileged=True,
-            verify=True,
-        )
+        if not driver_name:
+            self.send_command(
+                f"{self.devbind_script_path} -u {ports_pci_addrs}", privileged=True, verify=True
+            )
+        else:
+            self.send_command(
+                f"{self.devbind_script_path} -b {driver_name} --force {ports_pci_addrs}",
+                privileged=True,
+                verify=True,
+            )
 
-        del self._lshw_net_info
+        if self._lshw_net_info:
+            del self._lshw_net_info
 
     def bring_up_link(self, ports: Iterable[Port]) -> None:
         """Overrides :meth:`~.os_session.OSSession.bring_up_link`."""
-- 
2.55.0