Re: [Patch v2 2/2] thunderbolt: Teardown tunnels and reset downstream ports created by boot firmware

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On 12/12/2023 13:24, Mario Limonciello wrote:
On 12/12/2023 13:16, Sanath S wrote:
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 USB3 routers.
s/3/4/


Suggested-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Sanath S <Sanath.S@xxxxxxx>
---
  drivers/thunderbolt/tb.c | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index fd49f86e0353..febd0b6972e3 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -2598,6 +2598,17 @@ static int tb_start(struct tb *tb)
      tb_switch_tmu_enable(tb->root_switch);
      /* Full scan to discover devices added before the driver was loaded. */
      tb_scan_switch(tb->root_switch);
+    /*
+     * 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 (tb_switch_is_usb4(tb->root_switch)) {
+        tb_switch_discover_tunnels(tb->root_switch,
+                       &tcm->tunnel_list, false);
+        tcm->hotplug_active = true;
+        return tb_switch_reset_ports(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 */

Doesn't this cause the following to not run and thus break hotplug?

tcm->hotplug_active = true;


I think it would be better to do this like this flow:

     if (tb_switch_is_usb4(tb->root_switch)) {
         tb_switch_discover_tunnels(tb->root_switch,
                        &tcm->tunnel_list, false);
         tcm->hotplug_active = true;
         ret = tb_switch_reset_ports(tb->root_switch);
         if (ret)
             return ret;
     } else {
         /* keep existing tunnel flow */
     }

     tcm->hotplug_active = true;

     return 0;

That makes it crystal clear that hotplug isn't enabled until it's done being setup, which means either getting the existing tunnels or doing the reset.

My apologies I completely missed replacement call even though I pasted it.

Besides the s/3/4 this looks fine to me.

Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>




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