[PATCH v2 2/5] thunderbolt: Do not resume routers if UID is not set

From: Mario Limonciello
Date: Thu Mar 03 2022 - 08:15:51 EST


Routers 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>
---
v1->v2:
* Update commit message
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