[Patch v3 4/4] thunderbolt: Teardown tunnels and reset downstream ports created by boot firmware

[Sanath S <Sanath.S@amd.com>]

Boot firmware might have created tunnels of its own. Since we cannot
be sure they are usable for us. Tear them down and reset the ports
to handle it as a new hotplug for USB4 v1 routers.

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Sanath S <Sanath.S@amd.com>
---
 drivers/thunderbolt/tb.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 740bf2ff1fcd..462616e3075c 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -2596,12 +2596,27 @@ static int tb_start(struct tb *tb, bool reset)
 	tb_switch_tmu_configure(tb->root_switch, TB_SWITCH_TMU_MODE_LOWRES);
 	/* Enable TMU if it is off */
 	tb_switch_tmu_enable(tb->root_switch);
-	/* Full scan to discover devices added before the driver was loaded. */
-	tb_scan_switch(tb->root_switch);
-	/* Find out tunnels created by the boot firmware */
-	tb_discover_tunnels(tb);
-	/* Add DP resources from the DP tunnels created by the boot firmware */
-	tb_discover_dp_resources(tb);
+
+	/*
+	 * Boot firmware might have created tunnels of its own. Since we cannot
+	 * be sure they are usable for us, Tear them down and reset the ports
+	 * to handle it as new hotplug for USB4 routers.
+	 */
+	if (reset && usb4_switch_version(tb->root_switch) == 1) {
+		ret = tb_switch_reset(tb->root_switch);
+		if (ret) {
+			tb_sw_warn(tb->root_switch, "failed to reset\n");
+			return ret;
+		}
+	} else {
+		/* Full scan to discover devices added before the driver was loaded. */
+		tb_scan_switch(tb->root_switch);
+		/* Find out tunnels created by the boot firmware */
+		tb_discover_tunnels(tb);
+		/* Add DP resources from the DP tunnels created by the boot firmware */
+		tb_discover_dp_resources(tb);
+	}
+
 	/*
 	 * If the boot firmware did not create USB 3.x tunnels create them
 	 * now for the whole topology.
-- 
2.34.1