[PATCH 2/5] drivers/thunderbolt: don't resume switches without uid set

[Mario Limonciello]

Switches might not have a uid set if the DROM read failed during
initialization previously.

Normally upon resume the uid is re-read to confirm it's the same
device connected.
* If the DROM read failed during init but then succeeded during
  resume it could either be a new device or faulty device
* If the DROM read failed during init and also failed during resume
  it might be a different device plugged in all together.

Detect this situation and prevent re-using the same configuration in
these cirucmstances.

Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
 drivers/thunderbolt/switch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index b5fb3e76ed09..294518af4ee4 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2980,6 +2980,10 @@ int tb_switch_resume(struct tb_switch *sw)
 			return err;
 		}
 
+		/* We don't have any way to confirm this was the same device */
+		if (!sw->uid)
+			return -ENODEV;
+
 		if (tb_switch_is_usb4(sw))
 			err = usb4_switch_read_uid(sw, &uid);
 		else
-- 
2.34.1